Even if sed and grep are available their weird syntax is enough to make people write modern replacements.

I don't care if they're not 100% feature complete, the fact I can remember how to use them for my simple everday tasks (searching, finding/replacing across many files) without needing to consult a manpage or search online for answers is enough.

I used grep daily for years and _still_ it didn't feel like it made sense. I remember reading about Ack (https://beyondgrep.com/) some time in 2009-2010 , installing it and switching over entirely within about five minutes.

Modern sed:

https://github.com/chmln/sd

Modern grep:

https://github.com/ggreer/the_silver_searcher

https://github.com/BurntSushi/ripgrep