I think the bare โค๏ธ or ๐ alone, when no other reaction is available, is meaningless and could definitely be seen as diluting signal clarity. That said, I think reactions, where a much greater range of expression is available can add signal.
Zaps not only express that someone valued the content that was posted, but the magnitude of the value they found. Bit they don't express whether they found it thought provoking ๐ค, funny๐, hilarious ๐คฃ, mind-blowing ๐คฏ, or anything else that reactions can express (๐, ๐, ๐ฏ, etc), and which does take a bit more effort than merely tapping on a heart icon and moving on.
Not only that, but zaps don't gave any way to express a negative reaction, such as ๐คฎ, ๐, ๐.
So, zaps + reactions are great, but โค๏ธ or ๐ alone is terrible, and โค๏ธ or ๐ + zaps is redundant.