Also for multithreaded code, stopping one thread dead for long enough for a human to investigate it can inadvertently resolve all sorts of race conditions.
No one is saying breakpoints are useless, sometimes printing is 'cheaper' in time and effort in order to locate the region code of code in which using breakpoints is cheaper.
[0] https://docs.microsoft.com/en-us/visualstudio/debugger/using...
I don't think it is, at all. The cost of using print is re-running your applciation with a code change, whereas the cost of a breakpoint is re-running your application with a breakpoint. Clicking in a gutter in an editor, pressing a keyboard shortcut, or typing "b <line number>" into your debugger is no more time or effort than adding a print statement, and re-running your program.
If you have enough loops to make breakpoints impossible to use, you've likely got enough log output that you're not going to be able to parse. You're almost certainly going to look for other ways of narrowing the search space.
> stopping one thread dead for long enough for a human to investigate it can inadvertently resolve all sorts of race conditions.
Stopping one thread for long enough to do console IO has the same effect. Especially if you're using python, you'll need a lock to synchronise the print statement across your threads!
Once or twice? Any sane debugger has a way to disable the breakpoint.