Given that there are so many neutral changes, it does not have to be usually true. The fact that it is happening so often means you have many many shots on goal. It doesn’t matter if you miss, for example, 99% of the time. That 1% of success is enough to produce innovative shifts.
You often ask about the splicesome, which has over 300 some odd proteins. This is the best explanation for it. A large amount of unnecessary complexity that has become necessary.