I agree. About the only place where a frame-mounted front derailleur tab is warranted is if the frame has non-round tubing that a clamp mount would not fit.

I remember one of the 753 frames we built at Trek, where the buyer insisted on a braze-on front derailleur mount. He was insistent, so we did it. The frame came back a few months later. He had a bad shift on the front derailleur where the chain jammed, and the derailleur mount twisted and punctured the seat tube like a can opener. The brazing held, though!