We can argue the toss on that one until the cows come home, I'm sure, but it didn't help either, no. On the other hand, if the LibDems had decided to embrace Brexit, would you have been any more likely to vote for them? I'd assume not, as, let's face it, you'd have been right not to believe them. A pro-EU Party sticking to a pro-Eu position was, at least, honest.
The dominant problem that was exposed in 2010-15 was that the LibDems were too Tory for Labour voters, and too Labour for the Tories. Oh, yes, and the disaster of the Student Tuition Fees, which basically destroyed the core of their support almost overnight.
Actually, the entire story of the Coalition saddens me. It was the first time in a while that two parties were working together openly, and the effect has been to destroy the prospects of cooperation between any parties for the foreseeable future.