Has it really been that long? Apparently so. Valve originally announced their rebranding of Steam Play with Proton back on August 21st, 2018. Seems like a good time for a quick reflection being halfway to a decade old now with the tech that gave rise to the Steam Deck.
Going from a miniscule library of games that could work (I remember Linux Steam back before Proton having almost nothing of note) to opening up something pretty close to the entire Windows library and running Linux on Valve/Steam’s own handheld console for their games is indeed a quantum leap. That’s what Proton has done for Linux gaming. It may have gotten there eventually just with Wine and community contributions, but it would have taken possibly quite a few years longer to get there without Proton.
I think that is very subjective to the types of games you are interested in. For me Steam before Proton had so many native (indie) games that I literally couldn’t find the time to play all of those I was interested in.
So you agree that your interpretation was very subjective, and many people didn’t have the ease that you had?
No, because going from thousands of games to play to even more that you will never have the time to play is not a quantum leap.
If you had said Proton/DXVK made it finally possible to play a few triple A games I would have agreed. Still not a quantum leap though.