I think people who buy DE/SE razors often just like to partake in the accessories because they're selected from people who care enough in the first place to move beyond the cartridge razor. You certainly don't need brushes and nice lathers to use a DE. No more than you need them with a cartridge razor.

I have sensitive skin and a fresh DE blade cuts better with just water than a cartridge razor because it's sharper.

But before I got a DE razor, as an outsider, I also assumed you needed to take shaving seriously and be an accessories guy to use one, and thankfully it's just not true.