No one cares about the Spotify UI. People don’t interact with Spotify that much. They listen to it.
The business model of charging upfront isn't exactly a sign of popularity, if anything it's the opposite.
In a capitalist system how else do you measure value than what people are willing to pay enough for to have a sustainable business? End users aren’t paying for Slack. They are using the free plan because it’s good enough.
Are you just going to find a different reason why you're going to ignore software built on a web tech-stack? Add up the market valuation of all companies using web technology to bring software to their users. Then compare it to the native market. It's not even close.
It's perfectly fine to use market value to estimate utility in a capitalist system. You just can't ignore every piece of software you don't like.
And if you look at the end consumer software which have billions of users, who in one way or the other pay for it, it's almost always built on web tech these days. Discord, Skype, Slack, Spotify, and so on.
Of course there's professional or industrial software written in native code. But that's not because it's popular, it's because it's niche and specialised. The business model of charging upfront isn't exactly a sign of popularity, if anything it's the opposite.