you clearly don't know what the fuck you're talking about, that's soo funny to me
yes projection is a great indicator of proper singing, but stableness isn't. Too much weight isn't a proper term in singing either
if you want to play the game of fake ass internet vocal coach, at least do it properly?
You say you play guitar, but what the fuck does it have to do with classical singing technique? besides the knowledge of pitch, maybe ? my friend is a pianist, does that make her a good singer ? because yeah these dc girlies have a great sense of pitch if that's what you wanna hear, which is why you think they sound so good live. But that's not enough to make them the best vocal group or anything, that's all. a ton of kpop groups have vocalists with a nice sense of pitch and stableness, but lack a proper technique. dreamcatcher and most groups in general, even my faves fit among those.
and finally, sounding "powerful" isn't a proper indicator of one's being a good singer. id rather prefer a singer with a nice technique, a solid vibrato (which siyeon doesn't have lol) good support but a softer voice than one with an improper and dangerous technique such as dami and siyeon. these could damages their vocal chords, if you really was a fan of em id suggest you to stop defending their terrible technique :)
Visit google, type vocal weight, read. Thats why i said earlier, there is no point in discussing this bullshit.