Do these actually do anything besides collect mud? Chainstay bridge on my slackline is even worse than normal as its a flat plate perfectly positioned to collect a mound of mud next to the front derailleur (I know, how quaint, I’m attached to it thanks).
Can I just hack it off?

you could hack it off but it would probably change the feel of the back end for the worse and compromise the structural integrity of the frame

Yes, they do quite a bit to providing rigidity to the rear end of your bike.

I once had a bmx frame that didn’t have a seat or chain stay bridge, you could flex the whole rear end with your wrists.

On the upside, it did shave 40 grams from the weight of the bike.

< looks up from sawing >
huh wot?
< scans replies >
40g cool!
< carries on sawing >