Don't be sad. This is definitely a skewed perspective from a single person which makes it worse than useless as a way to gauge a random persons competence.

I'm sure you could find a person who would claim this same exact thing for any language if you searched around a bit.

To derive a useful conclusion you would need to control for all of the factors involved in the interviews and objectively measure their performance compared to other people's, anything less than that is completely useless at best.

I don’t think you have any good reason to think you’re inherently less competent.

The most important thing is to always be learning. You’ll never be done, embrace that and rejoice in it. Most people more or less stop learning in early adulthood: don’t do that, and you’ll eventually be ahead of the pack.

I took this post about F# talent to really imply -> F# has language features that protect or handle 'some concept', and then when the programmer was asked to do something else, they had trouble because they wouldn't normally have had to deal with it in F#. It isn't necessarily the F# programmers skill level, if dealing with other languages and needing more code to cover gaps, and knowing the gaps.

Can be a great Java programmer, now go do something in assembly, doesn't reflect on the Java skills.