That escalated fast by questioning the use of cycleway=* as an attribute of a cycleway instead of existence of infrastructure.
I guess another reason to deprecate cycleway=* in favour of cycleway:both=* to denote the existence of cycling infrastructure on both sides of a highway..
On topic: It’s definitively an interesting choice because “sidewalk” implies one can walk on a sidepath and not, well, cycle on it. However, a lot of ped-cycleways (both mixed and shared) are repurposed sidewalks and others are pure cycleways (with pedestrians discouraged / forbidden) which are repurposed sidewalk so I don’t think this tag will really hurt it per-se.