Is it meaningful to have dynamically created archetypes?

Currently isotope components work like "dynamic columns" for an entity, but they waste a lot of memory for entities that don't use all isotope components if they use storage::Vec for storage.

If we allow isotope archetypes, entities that use a particular isotope component can be abstracted out.

The problem with this approach is, in that case, we have multiple archetypes with the same combination of components anyway. In that case, why not just store them together?

Therefore, it seems isotope archetypes don't really make sense, since the root problem of isotope components is the need for a dynamic number of components without creating new entities.

Leaving this issue open for future reference.