There's a ton of different methods of multicolor printing each with different pros and cons - simplified
* nozzle that mixes from multiple inputs
* multiple hotends on the carriage
* swappable hotends
* single hotend - retracts and switchs to a different filament, few methods here, this is what the AMS and pallete are **
You can do it with multiple heads, the problem is ooze. You'll need to either be able to retract the non-used printhead so that it doesnt ooze onto your print, or be able to swap it mid print. Either way here you'll still need a method to prime it. Some materials may break down in the heat of the hotend too while they sit there unused just baking.
There's some methods that make the blocks smaller, like using the infill as the priming section.
In the videos I have seen it does both in the same print - poop and a waste block. But that might have been slicer misconfiguration. Although from the amount of times I have seen that makes me wonder: is the default config in Bambu slicer not taking this into account or all of the reviewers don't know how to configure their own preferred slicer. Just checked and 8/8 reviews of BambuLab A1 mini from channels that specialize in 3d printing showed purge tower.
Am I missing something? Doesn't the poop during change replace need to purge into a purge tower? Are there any additional purpose for the waste tower beside purging any remains of previous filament from hotend?
Both trade-off less waste for substantially added cost and complexity.
[1] https://github.com/zruncho3d/DuelingZero
[2] https://www.youtube.com/watch?v=1WqDcpxC3-o, https://github.com/ankurv2k6/wp-daksh-toolchanger
[3] https://www.prusa3d.com/product/original-prusa-xl-2/, https://www.youtube.com/watch?v=v3sSR2QvUyA