Let's tone down the misrepresentation and hyperbole, please.
Brutal irony/PKB for you to say that to me, given I asked the same from you, and you refused, a few weeks back. Still, peace and love is more my motto than "No quarter given!", so, sure. I'm not knowingly misrepresenting you, though, that's just my reading. I genuinely don't understand why people don't think any action is "taken" until, essentially, a roll is a made. It flies in the face of basic logic, for me. The action is "taken" when the player and DM agree that that's the Action the PC is taking this round. As soon as you're locked into it, anything related triggers, so long as it makes sense.
I'm surprised you can still say that after several people have argued for each side.
My interpretation would be that you have to take some part of your attack action at least, so make your first attack roll, grapple or other maneuver.
But apparently that is not obvious.
Indeed not, and I can't even make sense of that. It's not even literalist, it's saying "An Action isn't taken until part of that Action has game mechanic effect", which, frankly, seems to fly in the face of the looser rules of 5E, and to my mind, basic logic, and further, isn't, as far as I can tell, RAW or RAI or Rules-as-Implied, even. I'm genuinely not seeing where it comes from.
The guy you were responding to seems to be demanding "loophole-free" rules, and that's unreasonable, I feel, because 5E has intentionally set things up so the DM does have a role in deciding how things work at his table. Honestly, I feel like forcing people to take the Attack action THEN roll at least one attack is a strange way of doing it which overcomplicates things and slows the game down. It's certainly not some sort of serious "EXPLOIT!!!!" to allow the bash to come first.