Well, that's quite subjective. A lot of games are supported officially and many more work just fine although not whitelisted. So it's at least as viable as Wine and requires much less tinkering.
Very few games are supported officially (less than 1% of steam games). I only tried proton for one game (Age of Empires 3 - not whitelisted) which didn't work out of the box. I still think proton needs some work.
It's pretty obvious that not everything runs excellent and it's not that uncommon to find a non-working game. Consult protondb.com/ before buying/trying a game. Proton still expands the available games for Linux by a huge margin and it's only going to grow. My point is that mentioning Wine (which is not that easy to install/maintain) while not talking about Proton (which is already available on Steam and it's the most popular storefront for Linux) is kinda not fair.
I never suggested to use Wine directly. I recommended Lutris and mentioned PlayOnLinux instead of proton because proton is still immature.
You mention protondb - it has been discussed on several occasions that the website's ratings are not accurate.
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