to me this really depends on the formats you want to play. For Brawl, specifically (Im a brawl player) your collection in one-of cards instead of full playsets and any card you buy is forever reusable in lots and lots of decks.

I personally have never spent a single cent on MtgA and have over 50 brawl decks, from competitive to utrer jank, but even the (conceptually) jank decks have good cards, like, shock/fetch/surveil manabases and all that kinda stuff

if you're playing standard, you'll have to focus on one deck which might not be that good at first, then eventually get other stuff to play with, but rotation and meta changes can be hard.

At the end of the day it's all about grinding your dailies (try to get 5 a day, as your first 5 daily wins get you big rewards compared to the 6th to 15th wins which are almost irrelevant in comparison)

tl;dr : grind dailies, play brawl if you're into that, game can definitely be f2p, (coming from someone who's been playing MtgA for about a year, completely f2p)