If you double the number of keys and you double the number of bins (load factor stays constant), then the problem becomes much worse very quickly.
If you double the number of keys and you double the size of each bin (load factor stays constant), then the problem diminishes as you suggest. BUT, larger bins are more sensitive to changes in load factor.
If you double the number of keys and you double the number of bins (load factor stays constant), then the problem becomes much worse very quickly.
If you double the number of keys and you double the size of each bin (load factor stays constant), then the problem diminishes as you suggest. BUT, larger bins are more sensitive to changes in load factor.
The sibling comment ( https://news.ycombinator.com/item?id=40415826 ) does a good job of summarizing how post-2018 systems handle this issue.