Non-removable batteries are almost always the first parts that go bad in handheld devices, and there are absolutely no excuses for using them other than greed and incompetence.
Considering how important it is to keep Lithium Ion batteries within a safe temp range for longevity and the risk of thermal runaway I'm not so sure we will ever see easily replaceable batteries again without a new chemistry.
Everyone seems to have fond memories of their AA's and NiCad's but ignores that replaceable Lithium tend to suck... all my old phones that had replaceable batteries like the Google Nexus had batteries that got way too hot and subsequently lost their ability to hold a full charge
Your original argument is the one that's doging the fact that we are on a steam deck thread.