A typical story relevant here is that of a news site boasting about a rise in daily reads, where they define a read with being on a page for 3 seconds... that is clearly a meaningless number that maybe just means users are skimming through all your articles in hope that not all you have is terrible (could happen if you had some good content or a loyal audience)
And most importantly, even if my self-reporting isn't accurate, you don't know better, and telemetry won't tell you. If I say that I didn't press this button because it was red, you can doubt the accuracy of my report, but you don't get to conclude that my real reason was that the button was square and not round, or that it was on the left and not on the right. Or that the button is useless. Telemetry will only tell you I don't press it. Or perhaps you can run an A/B test to learn that I press the button when it's blue and round and on the right side (but you may miss the fact that I pressed it out of confusion, and reverted its effects three screens down the line).
Software developers are no different than real people, except that they have much more experience with computers - which means both familiarity with the UI and the ability to instinctively form a mental model of what's happening underneath, which sometimes leads us to intuitively avoid doing things that would break the application :).
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[0] - https://wiki.lesswrong.com/wiki/Egan%27s_law
[1] - Plenty of motivations could be embarrassing, or weird. E.g. for a long time, I avoided using GNOME desktop and related software, simply because I had a visceral revulsion towards their logo, which featured a footprint. It's a kind of motivation that did affect me, but I wouldn't be too willing to reveal unless asked directly.
[2] - Also people sometimes report on motivations behind what they want to do, but not on the incentive conflict they're facing, and they then proceed to do something you wouldn't expect. This leads to silly arguments like "something is good because of revealed preferences", which latch on the difference between expressed preferences and observed behavior, completely ignornig the fact that observed behavior is heavily incentivized, essentially making people go against their preferences.
Isn't there a decent amount of psychology research showing this isn't the case. Not with happiness with a service in particular, but that we poorly report on our internal state and often are biased by factors that impact our self reporting but not our choices. What people say and what people do do not always align and thus it is possible for there to be a gap between what people want and what people say they want. If you try to meet the latter you can end up losing out to someone who tries to meet the former.
Now, that is research on average people (and particularly average college students), so when dealing with software developers talking about software issues it may not apply.