No worries! I don't know if pollute is the word I would choose, as it again seems a bit strong and negative (imagine if you were a new mapper and someone says that adding a perfectly true elevation you saw on a sign during your hike to the database was polluting OSM!). So I don't even think the last sentence is necessary, but I understand where you're coming from.

PS As a consumer of elevations, you might be interested in this RFC (not by me) for a proposal to formally allow elevations in feet, if the unit is specified, following similar conventions for maxspeed=* and maxheight=*: https://community.openstreetmap.org/t/rfc-documenting-feet-as-an-an-optional-elevation-unit/108543