Over time they realised that, while holiday windows or whatever have high sales, if there’s a better or more popular game coming out then, yours will just be forgotten.
That said, most “industry specialists” are just glorified influencers, so take it with a grain of salt
With the amount of 9s and 10s coming out, why would you waste time with a 7? The polarisation is just an effect of the language of clickbait spreading in society, but doesn’t change the fact that average games are probably not worth your time.
The ease of use of the Steam Deck cannot be overstated. Yes you can tinker with it a bunch but if you just want to play your games, you download and play. The windows handhelds will never be as easy since windows is just crap for this (and MS is not interested in improving).
If you mean the switch, then it has been thoroughly squashed. If you mean phones, well I think we can agree they are not really competing for the same customers, and if you think they do, most people are buying phones for reasons other than gaming. So you’d need a way to section the market for “gaming phones” (yes, that’s a thing).