What are you talking about? Where do you think I got that from? That's exactly how D&D works. It is the D&D system. When you play D&D, if you go up against enemies and the DM awards you a thousand experience, that thousand experience is divided amongst the number of characters in the party. So, if you have four party members, they will level up much faster than eat party members, because you are giving more experience to each individual character in a party of four. So I can play the exact same campaign with four players as I do with eight players, but by the end the campaign with the four players will be higher level than the campaign with the eight players. I'm not entirely sure you fully understand how D&D works.
If we are talking about actual tabletop DnD, then open pages 82-83 of DMG for 5e. You don't only split XP based on the amount of players, you also tailor encounters based on the amount and level of players. On page 84 you will find guidelines for how much exp should a party member earn for each adventuring day. The actual amount of XP a single player in the party earns by the end of the day is supposed to be the same no matter the size of the party. DM creates encounters so that larger parties earn more total xp (more enemies, more difficult enemies) so that after you split the xp between party members they will level as fast as members of a smaller party.
Originally Posted by GM4Him
This is a D&D game, and D&D is never meant to be played solo.