I think it is less of a concern to the businesses buying these things brand new and more of a concern to the tinkerers who buy/repair/resell/use older models. There's a lot of people who still use ThinkPads made in early 2010s (and earlier). I had RAM module fail on an x270 and replacing it only required opening the laptop (RAM sticks just snap into place). If soldered-on RAM fails, it's game over, or at least full board swap.

Plus, no way to put more RAM/replace RAM with larger module if it's soldered on.