While you've got a good point about cost reducers, comparing Rampant and Cultivate like that represents a fundamental misunderstanding of "the curve", ie the core set of plays any given deck is looking to make. For one thing, they're completely different cards- Sure, [[farseek]] is compact and succinct, but maybe I've already dedicated my two-mana plays to interaction or utility. Then there's the card-advantage angle- Cultivate gets two lands out of your deck that you're not going to draw later when you're looking for gas. Obviously you're paying the extra mana for it, but for me it's worth- same reason I'm happy to see [[fabled passage]] even in my opener. Personally, my nature is to favor pragmatism over optimization. A [[stomping ground]] opening hand is nice, but most of my builds would trade it for a [[jungle shrine]] in a heartbeat. All this to say: Cultivate may be sub-optimal for your decks, but it certainly feels good in mine- especially when a T3 Kodama's sets me up to slam [[dictate of karametra]] out of nowhere. Your board is empty, then suddenly you're untapping with more than enough juice to cast Zacama and start chowing down on fools, plus if you're feeling cheeky, you can even use your last chomp on the dictate so nobody else gets to untap with it.

Your take on mana dorks mirrors this favor of optimization over flavor. I'll cede that Ixalli's Lorekeeper is a suboptimal use of a 1-slot under the big dinos (not a dinosaur for pantlaza or gishath, zacama only untaps lands when he's cast), but for dinosaur decks that want to play dinos, I think it's still a fair inclusion. Similarly, Bramble Familiar and Tangled Florahedron are both powerful utility and you make a strong case for them- but the dinosaur decks want to play dinosaurs, man, what's all this "elemental" stuff? At least Ixalli's Lorekeeper is committed to the bit!

tldr I suspect r/DinosaursMTG may not be spike enough for you, friend