Well, stealing is be defined as[0]:
> a: to take or appropriate without right or leave and with intent to keep or make use of wrongfully
Using Spotify without paying them, either directly or by watching ads, falls under that definition. The fact that there is no actual object being taken does not impact this.
If you create a great piece of software and I copy and then sell it, would you not consider it stealing? After all, you still have your copy.
Or, if a client contracts you to configure his network and then refuses to pay, is that not stealing your work? After all, you just used knowledge and time. Nothing stolen here, you still have your knowledge and you can surely make a copy of the configuration files :)
> The fact that you actually believe that you can buy their thoughts, their autonomy, their attention, and their time with your cheap crap doesn't mean if they opt not to give you those things you have been stolen from because those things were never for sale and you can't own them.
I don't believe you can buy their thoughts and I don't think Spotify attempts to. But you can definitely buy their time. That's exactly what you sell when you're employed.
> The best you can do is not do business if you feel like the deal isn't mutually beneficial. Take your ball and go home if you like but don't be dumb enough to call your users thieves for claiming unalienable rights to their own brains and machines.
Again, I totally agree. I would not use Spotify with Ads either. But if I'm not willing to fulfill my side of the deal, be it paying with time or money, I'm in no way entitled to their service.
[0] From: https://www.merriam-webster.com/dictionary/steal