"It is our goal to provide you with all the tools you need to make the most out of your investment in Mathcad."
That's an example of a very special kind of humour (or chutzpah).
Guess this only applies to the old, perpetual licenses which they don't sell any more.
With the new time limited rental licenses customers are under maintenance automatically, I guess, and so are entitled to report bugs. The effect at the end of course would be the very same - a non-bug-fixed piece of ... software.
So you may see it that way: PTC saves you the time to formulate and turn in the bug report. That way you have more time to make the most out of your investment...