One argument is that breaking the T&C is an act of resistance.
For all the talk about LLM training there has been little talk about how LLM inference could be a major countermeasure to
https://en.wikipedia.org/wiki/Enshittification
in that an LLM can read the ads and the spam and scams so you don't have to.
One could argue that the T&C is an unfair use of power in that a site like Craiglist has a major impact on the community which does not get to "consent" to it in any meaningful way. For one thing, there is the two-sided market phenomenon which means that a zombie site like Craigslist can prevent new and better competitors from appearing [1]. There's also the fact that craigslist and a lot of marketplaces suck: like you reply to somebody's post and you have less than a 20% chance of getting a reply, right now people on my local NextDoor are complaining that people make posts advertising house cleaning services but when they write to them they don't even get a reply saying that the services aren't available.
[1] the counter to that is going to be Facebook Marketplace