Newsflash! Riot hates Sona and never hesitates to go against their own design philosophies if it means nerfing her.
"We hate pigeonholing champions into being forced to buy a certain item to be relevant."
Yet Sona without LB is still useless.
"Abilities should be rewarding to use"
Hello, 1% movespeed per level!
"We reduced Sona's base heal and introduced missing HP scaling so she can't keep people topped up but is still impactful when people tai damage."
But we didn't say we wouldn't cut that HP scaling in half so her heal is crap either way.
Meanwhile, Nami heals and damages with one ability more than Sona with two. And speeds up better with her passive than Sona with her E.
Meanwhile, Thresh is allowed to be absolute top tier since release and is still absolute ungodly pain to lane against.