Thinking back more years than I care to remember, I’d agree with this. Unfortunately, I cruised through GCSE and a-levels, so coming out of my degree with “only” a Desmond was a bit of a wake-up call as I did a languages degree* and was considered one of the better speakers. it was the academic side that let me down, not the practical.
Sadly the “bit of a wake-up call” wasn’t enough and I went on to apply for the Graduate accelerate promotion scheme at greater manchester police – I failed to get on that, joined anyway and realised that quite frankly I wasn’t mature enough. Quitting that job made me grow up quite quickly
So yes, perceived failure can help you mature and grow. It’s an essential part of realising who you are and what you can do.
(*now a computer programmer and only use my languages for holidays. Still speak pretty well, but hey, I only went to uni to get drunk and not have to get a job at 18…)