“abutters” is not deprecated. There was some attempt in the past to deprecate it by people who did not understand why it can be useful.
As it is specified on the wiki, “abutters” applies to ways only (where landuse applies to areas normally). “abutters” can be used where you cannot draw polygons because you don’t have detailed satellite imagery in your surveyed area.
I think keepright is reporting abutters as deprecated because someone putted it in this wiki page: http://wiki.openstreetmap.org/index.php/Deprecated_features
which is something I can fix.
And here is what KeepRight says about “deprecated tags”:
As shown in http://wiki.openstreetmap.org/index.php/Deprecated_features some tags get replaced by others as new tagging conventions evolve. Consider this as a notice, not as an error. The term ‘deprecated’ is deprecated; you’re free to tag anything the way you like. This is just a hint for new tagging conventions that have evolved in the meantime.