I also have a Steam Deck, and I should make it clear the "ads" are the usual Steam Store stuff - entirely voluntary (you don't see ads for games unless you visit the Store page) and non-intrusive.
I think there's a world of difference between showing people ads for games when they visit a store page voluntarily, and showing people ads in their social media feed when what they want is to see their friends' updates.
I find it very weird as well. So a store shouldn't show products it sell? Only allow them to be searched?
I understand being anti-add, but we are talking about store here selling and distributing products. Which makes reasonable attempt to serve relevant suggestions to user. Of new games or games that are somewhat based on what users have already played or followed.
Now if Steam store was showing third-party advertisements I would be on barricades.
And no one actually forces you to use the Steam on Steam Deck it is linux box with root access in place...
I think there's a world of difference between showing people ads for games when they visit a store page voluntarily, and showing people ads in their social media feed when what they want is to see their friends' updates.