A Tippyverse is a setting where the D&D rules as written are largely taken at face value and as the basic rules for a world. (Originally used in the context of 3.5E; it's not quite as insane for 5E, but it's still pretty insane.) It can be an interesting thought experiment, but it looks nothing like any published D&D setting, nor like any homebrew setting I've encountered.Er...OK...whatever those are. Never heard of this one.
A world in which XP is treated as part of the "physics" is a world in which you can ascend to godlike power over the course of a month or two--if you survive--by going out and fighting a lot. Logical corollary: Every nation can apply this principle to mass-produce high-level characters. And since old age is very difficult to evade in 5E, it makes sense to put your trainees into the grinder as soon as they are old enough to have a fighting chance. The world is thus swarming with high-level teenagers, all of whom have gone through some form of standardized dungeon crawl. Lots of them die at the low levels, of course, but resurrection magic is readily available once you make it to 5th level or so (making you worth the investment).
Then have a look at spells of 6th level and up, assume that spellcasters with access to those spells are a dime a dozen, and you have yourself a Tippyverse.
This is why I treat XP as a narrative device rather than as game-world physics. Every so often, a group of people will go through an episode in their lives when they level up super-fast. It's not something that can be predicted or replicated or controlled. It doesn't even consistently apply to the same people--you may have spent years training as a wizard to reach 1st level, and then (when the campaign starts) you go into overdrive and level up to maybe 11, and then (when the campaign ends)... it just goes away and you're back to normal. If a new campaign starts 20 years later with the same PCs, you'll still be level 11. Does this happen to NPCs? Sometimes, but again--you can't predict or control it. Most NPCs have to earn their levels the hard way.