No. You do not have to use the auto loader to use editions.
Editions can be considered in the following parts:
A standardised editions property inside your package.json file used for defining the editions a package provides
This standardised property can then be utilised by optional things due to its standardisation, such as an auto loader that can automatically include the correct edition for the current runtime, or renderers that render the available editions for the consumers awareness. These latter parts are entirely optional, and should not detract or distract from the promotion of the valuable by itself editions property.
Are there other ways of doing this without making use of editions?
Yes, but they are all terrible, hence why editions exists.