It makes no sense to me when clothing manufacturers do this.
The ‘name’ of the size doesn’t really matter, so long as the measurement for that size is correct.
So, call them XS-S-M-L-XL-XXL-OMGXXL-EATLESSXXL if you want, but just make the measurements correct, so I know what to order.
I quite fancied buying a few of these bits, but pleased I didn’t bother now. I think I would have needed XXL, even though the size guide suggests that would be way too big for me.
The recent PSA on Freewheel for Pearl Izumi stuff was the same. I went up a size on the jersey & bib shorts I ordered, but none of it fit & had to go back.