Here's what I see in regards to our current digital platforms:
Facebook - began to replicate the AOL/Prodigy/etc "walled garden" approach very early on in their emergence into the mainstream. All links in were basically trapped, and any outward facing links come with tracking added to the URL (at the very least) and often the Facebook pixel, social media sharing tools and more. So you never really 'leave' Facebook. Fast forward to the present and the focus is on creating groups, pages, mobile versions of Facebook opening all external content in its own embedded browser and so on. And we were sold this bill of goods as a 'free' way to promote yourself or a product.
Google - quickly emerged as the dominant web search engine & got rid of the 'web portal' phenomenon. That was a wonderful move forward, as was the clean aesthetic and 'do no evil' mantra. Fast forward to now, and between 2016 & present their moves towards being a 'walled garden' are well documented ( see
The Hard Truth - Clicks Will Only Get More Expensive and Harder to Get,
Less Than Half of Google Searches Now Result in a Click, and
The Law of Shitty Clickthroughs for example). Building a website is still necessary once there's a certain amount of material to promote, and perhaps merchandise to use to prop up income streams, but it's not as simple as it once was to drive traffic directly to it.
Instagram - Well you already mentioned a good deal of what is relevant here, and that overlaps with other social platforms: image and style over substance, the appearance of 'progress' and a high interaction rate are the buy-in to branding here. It's not necessarily a bad way to support promotional efforts, but entire careers are made out of nothing more than selling image here at the same time.
Soundcloud - Once a blessing to the underground world, after it was purchased it has slid into trying to be another online music publisher. Still helps to carry content here, but they police the heck out of remixes and DJ culture alike, and have largely stagnated around a feature set that already existed prior to that purchase (rather than using the infusion of cash and stability to achieve anything further). At least it wasn't bought by a rapper looking for a fast cash grab like myspace was...
Bandcamp.com - One of the blessings of the modern musical landscape. Back when Soundcloud was still evolving quickly and Apple still 'sold' you musical files you could download and 'own', bandcamp was host to a bunch of largely unknown artists who benefitted from not having to know how to host their own website and could provide a minor sales stream. It was also a great avenue for certain artists (Love & Light Music for instance) to put out their content for free solely to drive gigs. Fast forward to today and many vinyl labels have found a second life on Bandcamp, and it's a legitimate means to distributing your music for profit AND can serve as a web frontend if you don't have the resources to invest in a web hosting solution that exceeds what they offer (the age of the popup flash website with some goofy interactive content and a few online shop links is long gone). Plus, publishing here has no restrictions on where else you put your content online (unlike some distribution contracts which limit you to their partners only).
Tunecore/ReverbNation/DistroKid/ADED.US Music Distribution/RouteNote/ONErpm/Octiive/LANDR/Ditto Music/etc - Since we're on the subject of publishers, this is the modern digital equivalent. Most of these are usable both as an independent artist and by labels, so the route you take now has more to do with what value a label or promotional team adds to your brand in return for their control over your intellectual property. On the flipside, all of these require a lot of effort and the return you get from most of the streaming services and portals they place you on will be meager without aligning yourself with a label or representation. This also goes for Spotify..but they have emerged a bit of an odd beast now as well.
Spotify - now allows independant artists to publish directly to their platform. Bandcamp still appeals more to the classic crate digging style of music discovery, where you drive the effort of finding new music, collecting it, and playing it back on your own playback devices (media players). Spotify picked up where last.fm left off in terms of playlist sharing, and evolved to be not just a competitor to Pandora/XM/Sirius and other 'streaming' services, but to have their own system of 'aggregate rating' schemes and 'AI' to 'learn your musical tastes'. So mainstream radio meets independent publisher, with the caveat that unknown artists will still remain relatively unknown without other means to improving their visiblity.
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Of course there's more, which is why I was curious what people think is an emerging play to visibility these days. If you dig into the links that are under my blurb about Google, most of them offer the suggested solution to get around the walled garden of "find new online advertising portals before others do". That might also be rephrased into "what is the next emerging online advertising strategy". Of course there's a zillion middle marketing managers out there that would love to discover this answer, but in our case what we would want to focus on is what's the next emergent strategy for our efforts?
Open to more thoughts...