D&D is a DM and players using a rather bad system based on what was popular 3000 years ago
In fact, it's so bad, it has persisted for nearly fifty years, indirectly spawned a host of imitators, helped keep the tabletop roleplaying game market afloat and provided countless hours of entertainment. Anyhow, as of this moment, the version of 5e D&D in Larian's attempt is closer to an M.C. Escher interpretation of the rules (as opposed to the rules simply as written).