re-entering comments: admin -m

[GuyBrush Treepwood]

At http://computing.ee.ethz.ch/sepp/cvs-1.10-to/cvsbook/main_78.html
it is stated:

"Invoking admin -m actually changes the project's history, so use it with
care. There will be no record that the log message was ever changed -- it
will simply appear as if that revision had been originally committed with
the new log message. No trace of the old message will be left anywhere
(unless you saved the original commit email).

Although its name might seem to imply that only the designated CVS
administrator can use it, in fact anyone can run cvs admin, as long as
they have write access to the project in question. Nevertheless, it is
best used with caution; the ability to change a project's history is mild
compared with other potentially damaging things it can do."

Is changing the history of a project a bad thing? And so it is, why? 
Could CVS have troubles doing certain operations on the project in the
future?