You shouldn’t put more energy into refuting an argument than the other person put into making it.
It’s hard to make decisions, because they always come with tradeoffs. You can try documenting those decisions, and you should. Those documents can have all the obvious pros/cons of every considered option, and they probably should. And sometimes, months or years later, somebody will come along asking how you chose Option A over Option B, and you will happily go dig up these old decision documents and send em over.
Sometimes the inputs to the decision were, in hindsight, wrong or incomplete. You could go back and rewrite the decision doc, and say “well here’s why we should keep using Option A, even though we have some regrets, because the switching cost is high, and we have a bunch of other decisions we’ve been making in the meantime that rely heavily on Option A.” You probably shouldn’t do that often; defending the status quo isn’t usually that valuable.
And then some argumentative person, or a reasonable person having an argumentative day, will come along. They’ll argue that Option B was always, obviously, the right answer. They won’t read your old decision doc. They’ll just bang the table and get mad that the past isn’t different. And you might be tempted again, to write that status-quo-defending-doc.
And you shouldn’t. Because otherwise you will be vulnerable to DA-DDOS (Dumb Ass DDOS).
See, making decisions is hard. Complaining about the results of a decision is orders of magnitude easier.
People love making low-effort arguments; and you don’t owe them a high-effort response.
PostScript: Thanks Steven Danneman for the name. Makes me so proud!