Can confirm that yes, it's incredibly doable. Probably harder for waifufans than for me because they've been releasing less and less male servants by the year but I've yet to spend so much as a single kobo in all the years I've been playing the NA release (technically since the London second banner but I also missed a year due to school). I'm also a super casual player even in games with more competitive features like granblue and A3 so while all my incidental spooks and summons leading to a good and powerful challenge quests clearers and farming teams is a nice feeling, I also spent these almost 3 years not caring because I roll servants for the satisfaction of keeping them in my chaldea.
That being said, the gacha is horrible and my not spending any money is less because I have some remarkable form of self control and more than Google play store literally does not accept my naira MasterCard so I can't use it to buy anything, and heaven knows I'm not interested in learning. The fact that after years and years these selfish pricks still won't add in an actual pity system and are satisfied milking as much money as they can when they realised this is the only franchise where fans good will is enough to turn them into masochists and keep the thing thriving just makes me hate everyone still in charge
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As for arguments on the Fate/TypeMoon/FGO/whatever. I've been involved with all of this for barely 5 years. I just consume everything new and old if it vaguely interests me, even stuff that I have a low opinion on like requiem is still something I want to see through till the end, I'm much to "young" to have any meaningful takes on what and doesn't work when the only form of comparisons I have for a before and after is the Naruto Vs Boruto Vs maybe Samurai 8 which I handled by ignoring the second since the first was already filled with flaws and dropping the third in chapter one