Trying to understand part of windowed algorithm

[IgorPerikov]

I'm trying to figure out, why (and does it?) this condition check for windowed limit is important https://github.com/Netflix/concurrency-limits/blob/master/concurrency-limits-core/src/main/java/com/netflix/concurrency/limits/limit/WindowedLimit.java#L155

It looks like under low load it wouldn't let the delegate limit to perform (while it probably should raise limit, especially if it was pessimisized before on overload)
And under high load it will work fine with averages, but with percentiles - you're either skipping too many samples(because they exceed window size) or letting actual logic not to be executed, because you will be setting window size to a big number. So picking window size became really tricky and hard to achieve properly