Some of the responses almost seem to indicate that manufacturing a sign cabinet with VHB, welding, bolts, etc. has to be an "either/or" scenario. The point, again, is that there are obviously limitations to what the tape will hold. Tape, stitch welds, rivets, screws and bolts all have failure points. Can every single cabinet in the world be manufactured with just VHB? No. With just bolts? No. The larger the cabinet, the higher the wind load, the more sheer force, the more salt in the air, etc., the more you have to adjust your attachment methods.
Sign cabinets are manufactured all of the time with just VHB tape. If you have a "small" cabinet sign, it's likely going to be constructed from 1" aluminum angle framing. The face (assuming it doesn't have to be removable for service) the returns and the back can all be attached with 1" wide VHB tape that is specifically engineered for aluminum-to-aluminum attachment and will meet or exceed engineering requirements. If you clean the aluminum properly and you apply the recommended pressure to the VHB when applying, the cabinet isn't going to come apart without some major event...but that same event would cause the same damage to a welded or bolted sign.
I've had to remove more than my share of aluminum faces that were attached aluminum framing with VHB tape. It requires pry bars and hammers. If you don't believe in the strength of VHB, you haven't tried to removed it.
Now increase the cabinet size and use 1½" or 2" aluminum angle covered with VHB tape. It's insanely strong.
3M has a very informative website. If you build signs, you should read up on the capabilities of their tape. I don't have it all memorized but as an example, one square inch of VHB tape will hold 20 pounds of sheer weight for a literally stupid amount of time. So lets say you have a 4' x 8' cabinet with 1" aluminum angle framing. You apply VHB tape to the perimeter of the face framing. That's about 24' of VHB tape. That's 288 of tape which will hold a sheer weight of 5.760 pounds. A 4' x 8' x .125" aluminum face weighs just under 60 pounds.
The stuff works. If it didn't it wouldn't be used by national sign companies and sign drawings wouldn't be approved by engineers.