Craig, you are an intelligent man with Significantly more knowledge in firearms than most, but you have always been a hater of the 500, and your bias shows. Is that a bad thing? No, we all have our dislikes and preferences. But why you think that every one should follow in your footsteps is beyond me. No gain? No gain over what? 475 Linebaugh? 500 JRH? Come on now. Not enough for a proper rifle cartridge?????? just what exactly is your definition of a "Proper rifle cartridge"? Just look at the ballistics, it has more muzzle energy than A LOT of "proper rifle cartridges" especially out of a longer barrel without a cylinder gap! Let me know if you want me to name a few of the more common ones. And yes I have read your response to such things before. Several times. Its either "not powerful enough" or "too powerful" depending on which argument suites your point better.
Not everyone wants to shoot a 2.5 LB single action chambered in one of those magnum revolver cartridges. Some of us don't want to get on a several month long waiting list and pay the kind of money required for a "custom" chambered in a cartridge that most stores don't sell ammunition for. Some don't want to carry around a beautiful custom sixgun through the brush when thy would cry if it were scratched. Some want it backed by one of the largest gun manufactures life time warrantee. Some of us don't mind carrying around an X frame, hell its never bothered me, and yes I have gone hunting with my 500 on several occasions. I am not terrified or heart broken at the thought of scratching it like I would be for a custom, well frankly because its not a super special rarity.
Now, here is a bite of realism for you; things have changed dramatically in the world of firearms over the past decade/century. The majority of gun owners and shooters these days are not avid hunters, and they aren't military or law enforcement. Most of my gun owning friends are lucky if they go hunting even once a year, many of them have never even been! It is topsy turvey from what it used to be, but they ALL love going to the range or the desert with their favorite guns. A lot of the things I see out there don't make much sense from a real world functionality stand point, especially taking into account who these individuals are. Does that phase them? NO. Nor should it. we are all in this because we love something about guns and the shooting and/or hunting sport. You love your custom 475 linebaugh, I love my factory 500 mag. I don't have much use or want for yours, you feel the same for mine. and that's just fine.
You are right, Marlin likely wont make an "affordable for the average Joe" lever action offering in 500 magnum any time soon if ever. The demand is not there like it is for an AR15 or 1911. Some one might give it a shot though, and its more likely to happen if people like us talk about it, and if or when it does happen, I will be one of the first in line to buy one.
PS I just re-read your post with the argument involving Indians and pack mules. what a load of baloney. What do Indians and gunfights have to do with anything? That argument is bunk because of the fact that there are some lighter weight offerings in the 500, I just went and weighed mine, it came in at 3lb 9 oz. that is hardly the 5lb beast you describe. There is also no good reason why a 500 lever gun should weigh significantly more than a 45/70 that takes the modern loads. so, yeah I really would actually think it grand to use a terrific cartridge like the 500 S&W in a rifle and have my 500 S&W revolver ready as backup. Even if I didn't, instead of having two more cartridges to load for like the 50 Jeffries, I can keep it down to one, regardless of whether I take them both on a trip or not.
and on what planet is the 50 Alaskan or much less the 50-110 better? you are comparing 1 cartridge with similar ballistics but harder to find bullets, and an out dated ultra long black powder cartridge that has inferior ballistics anyway, both have hard to find uncommon brass, and neither one is commonly sold in stores. and guess what? THEY ALL ARE LOUD with heavy recoil.