Both of these are wrong.
There are a fair number of musicians who do actively do magic with their music.
The other bard Russell ,
Signe,
Zor'lok,
Winslow, and
Chi-Ji, as well as Kyrian and their Mawsworn fallen kin, the latter of who
use music to debuff and the former who build all sorts of musical instruments
to purify or attack their enemies (hence all the music/sound based spells: Echoing Reprimand, Divine Toll, Resonating Arrow).
Nothing about evokers is based on existing game mechanics. This is hugely dishonest. First, the point of Evokers isn't combining magic, it's being able to wield multiple flights magic, their spells literally go from chromatic to focusing on a single color. Already this comparison isn't really accurate. Second, the dota character (I don't know why you'd bring this up when dota was just made up custom game shit) is
Invoker. Evoker isn't someone who mixes magic outside of DotA (which again, is Invoker). It's just a general term for a spellcaster, e.g. the entire basic "do damage" school of D&D magic being Evocation.