Mastodon (with an o, an often made mistake) has an API, which most alternatives (pleroma, gotosocial etc) also implement, partly. Several frontends, including extremely lightweight clients exist for this API.

Mastodon furthermore implements the whole server-server ActivityPub standard, which can be used for some actions, like following someone, just fine. This is a very well described standard.

Mastodon doesn't implement ActivityPub server-client standard, instead it has the aforementioned selfbrewn "rest" API. Which, IMO is a shame, and has caused all clients (mobile, web, etc) to rely on this nonstandard API.

Edit: the point being:there are several ways to get content from Mastodon, depending on usecase and needs. You really don't need to scrape or parse or load the JS cliënt.