Nice summation Greg, it would make a good "sticky" post if we did those here.Welcome to the forum!
The lids are not going to seal 100% even without shipping damage, and recteq’s position is that’s to be expected. The people that choose to seal them up with a gasket material like LavaLock do so for multiple reasons. Some don’t like the looks of the staining on the stainless steel where it comes out-that doesn’t bother me as I like patina on a well-used tool. Some believe that it keeps more smoke in the chamber, for flavor-above @Uncle Bob explains well why the physics of combustion says ‘Nope, doesn’t work that way’. Some don’t like the clang of metal on metal when opening the lid-I’m in that camp myself. Some want to direct as much smoke as possible through the smoke box of the RT-700s that have them, and I’m in that camp as well. There may be other reasons for doing it, but that’s all I could come up with this morning.
Frankly, it’s an expense and a pain to apply the gasket and not needed from a functional standpoint, other than directing smoke through the smoke box may give marginal benefits. My wife asked me to gasket her new RT-340 because she too doesn’t like the metal on metal clang, but the all-weather vents are gasket free. A search here for ‘LavaLock’ will, I expect, give you more info than you want on the subject!
I think part of what influences folks on this matter is commentary elsewhere in the general outdoor cooking universe. For instance, one of my charcoal burners which was built primarily as a griller, not a smoker, had lid, seam, and stack base leaks aplenty. I spent about 45 minutes sealing the various gaps with rtv and lavalock around the lid, a step I haven't found necessary on the RT. The difference is the fan and controller vs. only intake/exhaust flaps/gates. With the induced draft of the charcoal burner too much air was leaking in making temp control for smoking a bear. It was doable, but fussy because of too many variables. Once sealed it is relatively easy to control since it narrowed down the variables to two; intake ports, exhaust port. So what was necessary/useful from another form of outdoor cooker, might look like good general practice, but once aware of the differences in application, it's not a direct correlation.