Switch and SteamDeck are consoles. Just in a handheld form. Like any other system, the experience will be different. That is exactly the reason why people do comparisons, to find the right system for them. The size of the library might not be important for you, but maybe for someone else. Games are the reasons why people buy these systems. It makes sense to compare different things about the games, including its number of available games.

It is very important to know, because SteamDeck is based on Linux and historically there were only a handful of games (we talk about a few hundred) playable. So for people who wasn't informed before, its a good information to know that the library of playable games grew significantly.

but this is truly apples and oranges.

For you maybe. But the fact is, which you still ignore, that people are here to decide which of these systems to get. Both are handheld gaming systems and it makes sense to compare them, regardless of your feelings. Because people need these comparisons to find the correct device.

But saying one is “better” is kind of difficult.

Without comparing them, it will be impossible to answer which system is better. And I know which one is better for me, because I informed myself before purchasing stuff. And I'm sure there are lot of people who don't know how many games are playable on the Deck.