Brains recently got underrated. The way mcfly works is cool, but it offloads your habits to some “neural network” that you can’t control. There is not many methods slower than looking at unpredictable line-by-line output and almost nothing more anxious than a possibility of false choice done without thinking. This tool basically replaces a deterministic mismatch with a non-deterministic one. Your brain is good at predicting the former (because it is a neural network connected to itself) and bad at the latter, because two neural substances rarely agree.

My guess is that author wanted history-search-{for,back}ward in their .inputrc for up-down keys but missed that somehow. The default history behavior is undoubtedly tedious. https://unix.stackexchange.com/a/20830

The only thing I’d do to history-search- is to show a list of variants (like in wildmode=list:longest or similar) instead of presenting them one by one. Pretty sure it is already possible.