I love Glover and I am happy for him but I agree here to an extent, the reason Glover can stick around in the top 5 at 41 is because the division just does not have a lot of fresh blood. They have to scrap together challengers for Jones which is why they give it to guys like Santos and Smith on feeble sinning streaks over meh competition. In fact the video in the OP kind of proves this. A slow plodding fighter in his late 30s and early 40s who consistently gets rocked in the early parts of a fight would be in a career nose dive in the deep divisions like BW, FW, and LW. But at LHW, since he's a decent black belt with decent wrestling, Glover can just fight for top position and smash these guys.
Compared to the entire roster Glover is not an elite grappler, guys like Maia and Durinho and Gunnar are way better. Heck even on the same card Barcelos is a far better grappler. That said, Glover actually has a bigger grappling advantage relative to the rest of his division when compared to those elite grapplers because the overall grappling level in his division is so abysmal. Barcelos showed elite grappling but Taha understood enough BJJ defense to avoid getting finished despite being beat up on the feet and ragdolled on the ground. Even Maia often has to work hard for his finishes as he did against Neil Magny who understood how to use frames and hip escapes to defend or Matt Brown who had Maia on his back most of the fight but knew how to fight hands well enough to survive until the last 30 seconds.
Meanwhile, Glover just needs to get top position on a lot of these guys and he can often just camp there, pound on them a bit, get to mount with little work, and if they give up their backs he can often finish soon after and sometimes he does all this off the first takedown as he did against Misha and Cutelaba. Part of it is conditioning as well, a lot of these LHWs gas quick when forced to work especially if they're not grapplers. When Santos got reversed in the third round you could see he was completely demoralized and didn't fight the choke at all.