I have been typing grep -rn and find . -name for longer than I care to admit. They are in my fingers below the level of conscious thought. So replacing them was never going to be a decision, it was going to be an accident, and it was: I installed ripgrep to try it, aliased nothing, and a month later realised I had not typed grep -r once.
The honest reason is speed, but not in the way the benchmarks sell it. Yes, rg is fast, often several times faster than recursive grep on a large tree. The thing that actually changed my behaviour is that it respects .gitignore by default. Searching a project no longer means wading through node_modules, build artefacts and vendored dependencies. I search, I get the lines I actually wrote, and the noise is simply gone. That single default removed a whole category of "oh, ignore those matches" from my day.
fd did the same trick for find. The old syntax is fine once you know it, but it is a small language with its own grammar of -name, -type, -exec and the \; at the end you always forget. fd pattern just works, with sane defaults, colour output, and again the good manners to skip ignored files. When I do want the hidden and ignored stuff, fd -HI says so plainly. Compare:
# old
find . -type f -name '*.go' -not -path './vendor/*'
# new
fd -e go
That is not a small difference when you do it forty times a day. The cognitive load of the second one is near zero.
I held out on these for a while out of a sort of stubbornness. The classic tools are everywhere, they are on every server I will ever SSH into, and learning a replacement that might not be installed felt like a luxury. That objection is real and I have not fully resolved it: on a strange box I still reach for grep and find, because they will be there. But on my own machines, where I do the bulk of the work, I have stopped pretending the old defaults are good defaults. They were designed for a different era of filesystem, and it shows.
The wider lesson, and the slightly uncomfortable one, is that muscle memory is not the same as a considered choice. I had been using grep -rn for years not because I had weighed it against the alternatives but because I always had. Tooling deserves the occasional audit. Most replacements are not worth it, and chasing every shiny new CLI rewrite is its own waste of time. But ripgrep and fd cleared the bar by being faster and simpler and quieter, and that combination is rare enough to notice. I gave up on the old tools, and I have not missed them once.