Why the fake labels?

I find it really odd that violinmakers label their Instruments "Stradivarius" or "Guarneri" when they're obviously not from either maker's shop. Not just "In the style of Stradivarius" or "copy of a Stradivarius" but "Antonio Stradivarius faciebat anno 1772" in an old-style font. Like they're actually trying to fool someone.

If there's any other instrument whose builders stick fake labels on, I've never heard of it. Even crappy guitar, banjo, flute, etc., builders sign their work with their own names, not someone else's. Granted the Martin Guitar Company protects its brand far more aggressively than Sr. Stradivarius does, but why put on a label no one's going to believe?