There are many, many arguments detailled under this thread, I will quote again:
Boosting is bad because it:
- Help bots start profitting earlier and create an influx of new botters.
- Devaluate the time and effort that other players put into levelling new characters.
- Devaluate profession mats because people can boost alch/tailor alts to make transmute alts.
- Skew faction balance more, especially in horde dominated servers, as many guilds can now change factions easier.
- Fill the game with more fotm classes and specs, like hunters and warlocks.
- Make the community a lot more toxic, since a lot of unexperienced/new players will be in the same basket with experienced players, causing issues and everyone will start calling others out for being “boosted”.