I first learned it somewhere, then forgot, then not a single search result for "matlab post mortem debugging", then only found it from digging in my notes, so here be it.
I think that's perhaps because dbstop if error or similar isn't quite the same as what is probably usually meant by "post-mortem debugging" - you get to debug a still-live MATLAB process.
Yeah just superficial guessing. It's a super useful feature, think it should be mentioned in dbstop or even here. (Also I think you meant to comment on the answer)
There's likely a way to disable only it, rather than clearing all db stuff, but I'm unaware of what it is (it's not dbclear if caught error or dbclear if error).
dbstop if erroror similar isn't quite the same as what is probably usually meant by "post-mortem debugging" - you get to debug a still-live MATLAB process.