The game systems, Gatcha, and rarity tiers aren't directly comparable like this. In KamiPro, you only need 4 strong characters (specific SSRs) to make an optimal team that can clear all content, and even 2 will generally suffice. You don't even need to play Gatcha to do this. You can reroll until you get 1-2 of the SSRs you want, and then buy Miracle tickets ($50) that let you choose 1 character each. With $100 (over several months of play), you can easily make a team that's nearly as strong as the whales who spend thousands. There's also guaranteed SSR tickets, but those are lower on the diminishing returns curve.
KamiPro's entire reward system is designed around a steep diminishing returns curve. Each increment of time/money provides less reward than the last. That's why players who don't play much and spend little can keep up in progression with those who play all day and splurge--so long as you understand how to play optimally and reap the low-hanging fruit. And that's exactly why I wrote my guide: so new players don't spin their wheels and burn out.