They’re not wrong though. You might be thinking thermal resistance as in “can hold a blowtorch to it” in which case sure, bricks might win, but that’s not the context here.

R-value measures how quickly heat transfers from one side of an object to the other, a higher number means it insulates better, or resists thermal transfer.

A 4" brick has an R value under one. It’s like 0.8 or so. 1" thick plywood is already better at 1.25 or so. I think the OSB used as sheathing on the outside of wood frame houses is higher still but could be wrong there. Bricks objectively have worse numbers here

No bricks and concrete have high thermal mass, but they have fairly high lamda values making them very poor insulators

Bricks: 0.84

Concrete (dense): 1.4

Hardwood timber: ~0.15

Woodfibre board: 0.11

Plasterboard: 0.16

source

Wood and plasterboard is still a poor insulator compared to actual insulation materials (they’re around 0.035-0.038, with exception of PIR), but still much better than both brick and solid concrete.

Would you mind checking the R value of brick for me? And while you’re at it, check what an insulated wood wall’s is?

Brick and concrete have high thermal MASS, not resistance.

Again, please learn more about a subject before you speak so confidently on it. You could have looked it up real quick before posting

Bricks do have terrible thermal insulation. You are probably confusing thermal mass for thermal insulation.