Spammers are better at SPF, DKIM, and DMARC than everyone else

I'm sure regular airline passengers trip the metal detectors more often than terrorists, doesn't mean we should get rid of the metal detectors.

A better analogy would be a passport. It doesn’t stop all terrorists from boarding a plane at lest it stops already know to authorities ones (unless they have a passport on someone else’s name which is not easy).

Or perhaps, why do you lock the door to your house? A few solid kicks will open most doors, the locks can be picked, someone can smash windows and enter, and many modern homes can be entered by ripping the wall open with a crowbar and axe.

It's to stop midrange threats.

Doors and locks are purely social construct. For majority of people it's much easier to justify stealing from a porch compared to breaking in.

No more, no less.

For spammers on other hand it's just a business, there will be no reprecussions like ever and we know quite a few big and legitemate companies who started their path with marketing spam sometimes using leaked email databases.

The way you're using "justify" here, makes it seem as if you think people feel it's morally legit to steal, if it's on a porch for... reasons?! From a moral perspective, theft is theft. There's no way someone can sanely claim they thought it was a free thing, because it wasn't locked away.

Doors and locks are there to make theft harder, more overt, loud, etc, and by no means validate when it's legit to be a vile thief.

Likewise, all spam is spam. The use of tools to make it more difficult for spammers to be spammers, is the same as having doors and locks. It makes it more difficult.

edit: What I said was, you clained they tried to justify it. So no worries, I was not implicating you.