> This discourages thoughtful and frequent commits that express the intent of a change because all the commits are just smashed together anyway so why bother.
This is only the case if said squashing just bundles commits without context or consistent logic. If merges to a mainline branch consist of feature branches whose pull request was already approved after a couple of iterations then the end result is a cleaner commit with it's history thoroughly audited. In practice it's equivalent to a fast-forward merge of a single-commit feature branch that just happened to be nearly lined up with mainline.
This is only the case if said squashing just bundles commits without context or consistent logic. If merges to a mainline branch consist of feature branches whose pull request was already approved after a couple of iterations then the end result is a cleaner commit with it's history thoroughly audited. In practice it's equivalent to a fast-forward merge of a single-commit feature branch that just happened to be nearly lined up with mainline.