You mean as opposed to the last 20 years where it wasn't the standard? That ship has sailed. If Linux wants to stay relevant to end users (particularly gamers), it needs to be accessible. Proton makes gaming on Linux accessible, regardless of what the Linux purists may prefer.

I'd be using Linux full-time if I knew all the games I played would work on Linux. They don't, so I end up using Windows way more than I'd like. Proton is the only way out of that.

Perhaps for now, but if Proton raises the Linux gaming market share, companies in the future may be more likely to invest resources into native clients.