But as a lay person, the explanations seem weak.
And, as a lay person, the Darwinian/Fisherian explanation of sexual selection seems to me to be overwhelmingly obvious.
But I, like you, am a layman. So perhaps we should look at what
scientists have to say about the subject.
You don't want to go there.
Darwin would not have arrived at his theory by contemplating the crazy plumage of some birds; rather, he had to find a way to reconcile the plumage with his theory.
I have noted before that not only are creationists wrong about science, they are wrong about the
history of science.
I wonder about any cases of organisms with features or behaviours that do vex scientists as to how natural selection is responsible. I wonder if, starting with natural selection as a given, there are cases in which scientists struggle for an explanation that fits in.
Well of course at the cutting edge of science scientists are always "struggling for an explanation that fits in". That's their job.
But to answer your question in the spirit that it was intended --- then NO. Biology and evolution fit together perfectly.