Both learning and the ability of tools are gradual though. For doing naive substring search all grep-alike tools works perfectly, and anyone who are willing to spend some effort and learn a bit of tool-specific features can gain a lot more more benefits.

rak is backed by the entirety of raku language and therefore is much easier for some crafting something that's less trivial to generalize in a one-liner. For most of grep-alike tools, their regex engine would be some sort of ceilings of what can be done but for rak, the ceiling is as tall as the raku programming language. That's rak's niche.