On the bright side, those are probably the companies you don't want to work for. It is one of the signals for bad company culture.

So in my own experience, older colleagues can usually bring two things to the table regardless of relevant work experience: maturity and responsibility. This isn't always true (I've definitely had some older colleagues who are exceptions to this rule), but I think probably your average 40 something is more mature and more responsible than your average 20 something. More importantly, if someone went and did this degree in their 40s, I know they are doing it because they really want to follow the career path that the degree leads to, not because they chose this academic program at random at the age of 17 or 18 because they weren't sure what they wanted to do.