As someone who's been a hardware engineer at Apple and left specifically because I saw they were getting rid of the headphone jack, it is not the engineers that get to make those kinds of decisions. The decision to remove the headphone jack was so they could sell you $100+ air pods that would then also work with your Apple Watch. It was not because there was no space or that ingress protection was unachievable, or it cost to much, or people didn't want it. Trick Dacy is right.
By the way, I rock a Linux phone now with a headphone jack, removable battery, microSD, and have an Android with a headphone jack, microSD as my backup. If the Fairphone 6 had a headphone jack, which is the #1 requested feature on every forum post I've seen, it would be the perfect phone, especially given it can have both Android and Linux on it.