yeah, using a phys damage weapon doesn't make much sense, same as a phys goblet or the BC set. in exchange you could use the new cryo set and another weapon which might even give you a damage increase. can't say anything about xiao/john lee, but the others should be fine. xianling could even be great for her own melt combo since EM is her stat and anything else boosts ATK independent of type. keq can be run as phys, which would then just become cryo for SC triggers. would make her first passive pointless, but the SC would make up for it, while still giving you electro for the time it's on cooldown.
beidou's (at least on paper, who knows how it it works under the hood) should be able to trigger her own SC too since the 20% electro are on top the normal damage and scaling from it, doesn't need to be phys, and doesn't infuse (and the 20% only trigger after taking damage, which you don't want if you use serpent spine, so there's that too).
you could probably make it work with most of the chars, it just takes a bit more effort than what people usually do with "take weapon with highest number, put matching ele set + goblet on char, mash button".
don't forget pyro + dendro applies a dot, shit's gonna be even more whack in the future. and if they nerf it (which they have to do at some point) the chinks are probably get pissy again.
