It seems that both Steam and Spotify addressed this by becoming the dominant player in their space. Yes there are alternatives to Steam on PC and there are alternatives to Spotify, but those two have the vast majority of the content you are looking for.
Video streaming was like that for a while. You had Netflix and it was the king in town, but then all the other services started to roll in and take their content off Netflix.
I find it to be this wired tug of war between buisneses and consumers. On the one hand as a consumer you almost want a monopoly in the space as all your favorite shows or music will be on one platform (like Spotify). But we all hate monopolies so from the business side you would want healthy competition. The problem is that "healthy competition" means you now have to subscribe to 10 services instead of 1.