The way I see it, as long as the parents want you there, and it's not affecting other aspects of your life, AND you're a help rather than a nuisance (doing chores, reducing their workload, etc), why leave? Very different to be in student, or a working professional living at home vis a vis someone who doesn't do something to further their lives. (note the definition of something is flexible)
In GTA it definitely seems like a good idea to save for a down-payment while living at home. If I end up there, I'll likely stay with my dad for that reason, provided the commute isn't crazy.