In this case, this road had been tagged with ref="IL 137" for 13 years before you removed it. The other roads that I touched were similar; I am only restoring these to how they had been for a long time. What percentage of state highways do you think have not been tagged like this?

And again, I mentioned OSM carto because it is probably the most well known consumer that uses way refs instead of route relations. That being said, there are likely many other consumers that look for way refs too. With how significant of a tag this is, we could be affecting a lot of people by removing the data.

As for my process in restoring the way refs, it wasn't only based on way history. For each route, I only touched ways that were in the corresponding route relation, and I also consulted Wikipedia to determine if the path that it followed is current.