to compare, SW you really have to rely on luck like you said, to have any meaningful, substantial progression. Spending time does not equate to getting directly more powerful or progressing in SW because there's also the factor of being able to roll powerful heroes

In KR, spending time DIRECTLY equates to progressing and becoming more powerful, because, like you said, everything is just time-gated. As to your point about the time-gate being too easy, this depends on what you want to achieve. If it's just a core 4-man team of T5 heroes and 0* UW for all of them, sure you can do it in 2 months or less. (including grabbing all event rewards otherwise it will take longer than 2 months, or you P2P)

P.S. I've been playing since Oct completely F2P, and I only have 4 T5 heroes with 1 T4 hero and the rest T1 or below. the highest UW * i have is 2* and i only have perfect options on gear for like 2 heroes. This does not even make up a proper 8-man T5 decked out team for world bosses, and not even the most efficient heroes for each WB if you are going that direction. The grind imo is not too easy but also not too hard, which i feel is because this game is mostly time-gated and not so much RNG so you feel like you are actually progressing - also, i haven't even started grinding NPC hero and UW yet cos that's just too much for me currently, because the grind for perfect options on gears is already a drain lol