Spotify does that and it's a complete deal breaker.
I want to log in to all my home devices _once_, with a single account. Not continuously log out and log in and try to type complex passwords with a remote control. I mean, I can't even play different songs on different Google Homes or different TVs with Spotify, unless I sign in with different account on each - and then each device is stuck with a specific set of playlists. Horrible.
Netflix's system has worked out brilliantly for us - we have half a dozen TVs, and any member of the family can watch anything they want on any TV with their own preferences and profiles with minimum hassle.
Again, the use case is different.
What you describe: If you are an individual, ability to login same profile on many devices is sufficient (both netflix & spotify do this).
I'm talking about family use-case with multiple devices.
With Netflix, my wife, myself, our kids, anybody, can click a profile button on any of our devices (TV, tablets, phones, etc) and simply continue watching what they were watching, get their recommendations, etc. Crucially, they can watch different stuff at the same time on living room TV and basement TV, with no hassle.
I have opened support cases and there is currently no way I'm aware of to do that with Spotify. I have Google Homes in all the rooms, and I want to seemlessly play different stuff in different places. To do that, I have to create as many accounts as there are devices (that's a LOT!), AND each device is now locked in to their playlist/song/etc.
The underlying difference of paradigm is: 1. Netflix - single account with multiple soft profiles. You can watch as many streams on same account as you paid for, hassle free
2. Spotify - multiple accounts loosely linked solely for purpose of billing. Each account can not stream multiple places. So if you want to stream something on three devices in parallel, you have to a) Create three accounts; b) log in separately with those accounts in each device. What when I have dozen devices? (4-6 Google Homes, 6+ tablets and phones)? It is now insane to do anything.
Basically we now exist as isolated islands and have given up on listening to music in kitchen and family room at the same time. This is awful.