Minecraft different biomes have different things to offer players. Honestly, it’s impossible to get your hands on every item in the vanilla game unless you go to the different biomes and collect resources that are unique to them, like the slime balls you can get from slimes which only spawn in swamp biomes. The Biome Adventures map is more about parkour than Survival though, and it has players running and leaping among floating blocks and towers as they move from one biome to the next. To be fair, there is an actual world down under your feet if you want to take a break for normal gameplay.
However, it’s clear that the main appeal of the Biome Adventures map is the parkour, not so much the map itself. The various towers you find standing around actually serve as checkpoints, and every time you make it to a new tower your respawn point is changed accordingly. Alternatively, there are smaller, diamond islands that will allow you to do the same thing. Once you’ve cleared the course, you can always go back and hack up those islands for free diamonds too. If that’s not enough, the course actually has 15 hidden chests and a horde of diamonds built into it as a secondary challenge.