Many devs tend to over-engineer things whether they are at a startup or not simply because they like building things, that's why they are software developers. I don't think this phenomenon is much more complicated than that.
'Over-architected' and 'over-optimized' are the terms I prefer. Whatever term(s) is(are) used, criticism should emphasize 'non-pragmatically-built', instead of emphasizing 'startups don't need any design, engineering, or optimization, whatsoever'.
