Hmm, that does explain why it’d need mortar, too. The tongue and groove stuff works like puzzle pieces and if you follow a lot of the other advice, it’s not a terribly hard diy project. There’s cheaper stuff out there, too, though you definitely notice the difference.
Listen, as someone who fell in love with a trans woman decades ago (my ex), it’s more plausible than you’d think. I didn’t go shoot up people since I wasn’t raised right wing, but love does make you do crazy things!