As someone who has done some of the most extreme/risky forms of travel hacking (serious FD's with 1X + sX for those familiar with lingo), Matrix lost a huge amount of its value when it disallowed searches that start from multiple countries. It's tedious to have to break up a search. Of course, this is not necessarily what they intended it for, so I can't really complain too much.

And covid uncertainty these days has made proper flight hacking a bit of a pastime.