If you're familiar with the logistics of the components industry, you might understand.
You're completely glossing over the connection between these things. New hardware line coming out this month-ish(?). They also want it to be successful. The product overlap is with the Frame, Switch 2, Arm devices at large, and the myriad other handhelds trying to copy the success of Deck.
Now, if you're Valve, your bread and butter isn't the devices, it's platform lock-in. More devices running Steam means more money, regardless of the device itself. This is why they've taken the time to make sure SteamOS was portable enough to run on a bunch of other devices, which is the big note here.
They're thinking platform, you're only concerned with a single piece of hardware that had a miniscule impact on their bottom line. They make BILLIONS in pure profit every year ust from platform engagement. Deck made them millions over four years. That's the difference.
So what makes more sense? More Deck models, or more devices spreading into a larger ecosystem to gain further footholds into platform engagement?
Deck honestly doesn't factor much into that. Frame and FEX however is going to be monumental shift into a massive expansion of Steam on ARM, and will probably ultimately mean if there is another Deck, it's also going to be ARM. It's a much bigger picture than all the comments in here are putting together.