Chemistry might not be much better. It’s because scientists generally assume that readers already know how to do the techniques, and so the only information they would care to provide are the ones that wouldn’t be considered obvious. Such as equipment brand, the name of the technique if there’s multiple techniques that do the same thing, or experiment-specific modifications to the technique.

My understanding is that it’s a holdover from older times, when scientists were charged per word, and so methodology would be cut down to remove anything considered “general enough” knowledge

If you’re asking scientists about writing protocols, you clearly don’t know how scientific protocols work. If anything, scientists need to take lessons from recipe writers on how to write protocols. Scientific protocols are notoriously difficult to replicate.

Here’s a burger recipe written like a scientific methodology:

Raw beef patties (Carshire Butcher) were prepared on a grill (Grillman) according to manufacturer’s instructions. The burger was assembled with the prepared patties, burger bun (Lee Bakery), lettuce (Jordan Farms), American cheese (Cairn Dairy), and various toppings as necessary. Condiments were used where appropriate. Assembled burgers were served within 15 minutes of completion.

Seems likely that it’s dropshipped. So I would wager there is no real source