continue to do what advertisements tell you to do, I dont care.
I got the recommendation from an AV tech to use Malwarebytes and an antivirus. No advertisement involved advice involved.
Malwarebytes is great, but you dont need it running all the time, just scan when you have a reason too. Defender is noot the same it was years ago, anything getting past it will also be getting past premo antivirus. And most "mainstream" antivirus will intentionally give false positives so people feel like its doing something when it blocks stuff.
The point is, if defender doesnt block it, its getting past in a way that most antivirus wont catch either.
You may well be right BUT...
I have had to reformat my PC about twice a year due to virus infection of some kind for about 15 years before getting Malwarebytes and not once since I got it have I had to reformat. Let me repeat that a little more clearly in 15 years I reformatted at least twice a year due to virus-like activity on my PC, then I got Malwarebytes about 10 years ago and I haven't had to reformat since. After getting Malwarebytes free I decided to upgrade during a sale, when I did I found out it also acts as an AV I stopped wasting time with other AV programs. I have gotten about 5 files that I just couldn't download because Malwarebytes stopped them for "suspicious" activity.
Now in response to "if defender doesnt block it" is not a problem defender blocks more downloads and programs because it is to simplistic a scanning process AND Malwarebytes will let you download and scan programs after unzipping them. You are correct that most virus programs getting through windows defender will get through most scanners BUT...
I'll put my $50 a year subscription or my $0 free use version against your "free Windows enforced security program" put out by a GUI programming company that is 100% focused on selling the next version of Windows rather than actually preventing infections every day and at the end of the test I will have more working programs available to me for doing it.