Whilst I know about muffins, I can't tell you why the Thomas's ones are not good; although I note that Ruhlman says:
"...Btw, if you’re buying English muffins, I highly recommend Bays English muffins, which are flavorful perfection; avoid the doughy, flavorless, but ubiquitous, Thomas’s." This quote links to his recipe for the type of muffin made with a pancake-like dough.
There's then those muffins with a lower water content. Here's examples from Jamie Oliver and Paul Hollywood:
https://www.bbc.co.uk/food/recipes/engl ... fins_56640https://www.jamieoliver.com/recipes/bre ... h-muffins/Given that this method of cooking bread pre-dates the common use of ovens (They were baked on a steel plate called a
girdle over a fire) I would think that the recipe was fairly simple - more than likely flour, yeast, salt, water and maybe a little lard. The flour wouldn't have been anywhere near the same gluten content as modern varieties either.
Have a play with those recipes, hopefully one will fit the bill.
Phil