Chalk weakens your rope - by a lot!
I'd bet you’re probably not too concerned about getting chalk on your rope.
You might be after you watch this video below.
Edelrid did some interesting testing upon how chalk can damage your rope. An 80 kg weight tied to a short length of rope was repeatedly raised and lowered over a carabiner.
In one test, the rope was clean.
In another test, the rope had chalk rubbed directly on it.
While I recommend watching the whole video, here's a summary:
The clean rope lasted a very long time - 200 cycles and no damage. (Cool, that's how we expect a rope to work.)
The rope with chalk rubbed directly on it showed some clear damage after only 10 cycles! Yikes!
The rope sheath was completely torn after only 16 cycles! Double yikes!
Wash your rope. Keep it in a rope bag, whether outside or inside at the gym. Use chalk with a bit more caution and yes, even you dirt bags, wash your hands sometimes.
There are a lot of great nerdy tech videos like this on the “Edelrid Knowledge Base” YouTube channel and on their website. Give them a follow if you don't already.