you didn't read did you? i clearly said "powerful enough"...
say you get Trish.... well grats, you got a kami that will last you a long time. Even someone like belobog and possibly light caspiel can hold you for a moment... But say you pull a lower tier one like Light Perun... she's just tower fodder. see what I'm getting at?
and there's two kinds of power creep this game has. Overall (as in not looking at element and looking at overall kit), and elemental (the best things of that element. my example was that a fire kami coming out to reshape the "overall" meta doesn't shift the "light meta". that fire kami will shift the "fire meta" though.
and who said you NEED managarmr? yeah she helps a ton but a soul weapon with a high event eidolon is like what, 40% from the eidolon (maybe 45% or 50% if you get those ones) and 30% from the weapon? that's 70%. and even if you don't pull mana, if i got something like an MLB thunderbird (60% light and thunder elem attack) to go with my herc axe, that's 90% elemental attack. what you would need is a friend mana to pop up. assuming i got all that and no matching eidolons in my sub slots, still 60% +30% +80% for a total of 170%....
again, become "powerful enough" then decide if you want to chase after more. and honestly, given my current light team, i'd only really need SSR atremis to hold off on light chasing for a long time since my front line can still consist of sol, tsuki, eventually AW mike, and a choice between other light SSR i got. while a free player doesn't likely have that luxury, i don't see a need to burn more money on light kami aside from 1 more miracle ticket. the rest is just preference...
if you happen to get such power, then kudos.... but given how RNG heavy and grind heavy this game is, "meta" is unfeasible unless you throw tons of money at the game... likely 2-4 times as much as i have and that's saying something considering i'm looking at almost 175 kami... yet only 3 kaisers (which only one was a lucky roll from the gacha) and NO 100% eidolons...