It requires very little sealant to make an effective seal. I don't use the heavy silicone gasket compounds, only Permatex Ultracopper, so I can't speak for how well they do or don't work. The Ultracopper is used on literally many hundreds of engines without using a gasket, and has been for years. In every application it is applied as an extremely thin film, with every effort to eliminate any chance of oozing into the path of exhaust gasses. Any lip or ridge created inside the port reduces exhaust efficiency, and performance. For some, any reduction in performance can be a critical issue.

There's no need now, nor has there ever been, a reason to apply a thick bead of sealant. 1/64" is actually quite thick for the intended purpose of the material. Those that have had issues with screws backing out of the muffler may have failed to use a thread lock compound, used the wrong kind of thread lock compound, failed to install a support bracket on the muffler, or used screws of incorrect size. Not using a fiber gasket has not been the cause of loosening screws. The opposite is generally true. By eliminating the gasket the muffler generally remains attached much longer, especially when a support bracket is also used on the muffler.