Yes indeed, but they are not alone. Just about every software company stops supporting something at some point.
I have no problem with the idea of dropping support for old software, that's just what you have to expect today. But this is a bit different.... Garmin carelessly broke it and then immediately pulled the plug without fixing their mistake. So a user could have been happily sending maps to their GPS. The very next day, using the same computer, same operating system and same GPS, they get a message about Basecamp auto-updating. Now they cannot send maps anymore, Garmin has no method for downgrading and if you call them I'm sure you get the standard "sorry, but we don't provide support for problems with third party maps".