In my opinion if they hide stats, it’s because revealing a too high number would create a bad buzz on their brand and risk to drawn them.
They must not be good at all for FP2, which was their first entirely home-designed and modular smartphone. They could’ve drown just with the repair costs, which I think is why they’ve made a fundraiser for FP3: they didn’t make enough benefits with FP2.
For FP3 the stats must be much better though, I think you’re unlucky: I’ve used FP2 warranty to the latest second for almost all parts of the phone at least twice each, however except for the falling letter of the backcover, no major issue on the FP3 that need me to send the phone or ask for a replacement piece yet. So it’s still not perfect at all, remember it’s a small company which innovates a lot.
They don’t want to create bad advertising with bad statistics. However I agree with you I’d love them to be fully transparent. They might reveal the full numbers one day, if they can resist the consequences, but not sure they will: it could only hurt them if they’re too bad, which I think is the case.