Rigid rules means you can't adapt to reality. Adapting to reality is necessary for good software development.
Sometimes you just can't let something else wait until you are done with what you were doing. Sometimes you were doing something that can't meaningfully progress until something else has been fixed. Rigid computer enforced rules like that just mean that people will have to work around them, wasting energy and producing the wrong things.
WIP limits shouldn't be rigidly enforced. Instead a warning should show when you are over WIP, and some stats gathered in the background. If your team goes over WIP occasionally, it's usually fine. If you go over WIP a lot, your process is broken somehow. How, when, who and where you went over WIP can give you a lot of info on where your bottlenecks are and how to improve your process.
I've been on a Kanban team for the past year now and I can say with confidence that if our tool didn't track WIP, we would be less effective as a team.
Sometimes you just can't let something else wait until you are done with what you were doing. Sometimes you were doing something that can't meaningfully progress until something else has been fixed. Rigid computer enforced rules like that just mean that people will have to work around them, wasting energy and producing the wrong things.