I both agree and disagree. I agree that there isn't going to be a single 'straw', because everyone's thresholds are different. For me it was back when Microsoft auto-upgraded my PC to Win 8, which was also when they started putting in hard-to-disable telemetry and bad UI. It sounds like Recall is the threshold for some other people.
Also don't discount that MS' market share is dominated by a ton of corporate users (who lack a choice) and casual users (who don't care / are unaware), but at least anecdotally they've been losing the power users in my life, which if true in general which will have negative downstream effects for them moving forward (IT departments working to support alternatives, software developers refusing to build on Windows Server / MS software stack, etc.)