It is also for identification, however it is also (more importantly) for insulation to prevent the wire making contact with any other conductor. It would be too easy for the wire to fold against a bit of exposed live conductor when you tuck it all into its back box. In the case of it contacting the phase, this would cause an immediate earth fault that should trip the protective device. In the case of the neutral this could cause subtle nuisance tripping problems with RCDs.
Part of this is a design limitation of some saws where the crown guard can't be remove without also taking off the riving knife. Things like tenons, dados, trenches etc can be cut with a riving knife present. The only operations where the knife will certainly cause a problem (that I can think of) is cove cutting, and plunge cutting.
Crown guards can be used far more often if they do not require support metalwork that passes through the line of cut.
Generally, dado sets or equivalent tooling involve taking off the riving knife, and in any case it doesn't do anything useful in the case of a groove being cut.
On larger industrial saws, this is done by having the guard cantilevered and on rollers covering the whole blade area. e.g.
one such as that that Axminster sells (056002) which is flimsy junk.
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