I guess whether it's right or wrong, depends on how/if the contest director applies the Builder Of the Model rule. Perhaps ARFs in scale contests can fairly compete in team scale, since there's the Flier/Owner, then the Builder - a Chinese* dude stamping out the airframes on an assembly line.

*Feel free to replace Chinese with any other nationality, of course. No offense intended.

The hobby has changed over the last 10 or so years, with ARF's proliferation, and the focus now is how to get the model in the air faster. Many ARFs are less costly than similar kits. But I'd think without keeping ARFs separated somehow, there's less incentive to compete with a model that has been built by hand, rib by rib, and bulkhead by bulkhead... Aerobatics contests rewards fliers that are dedicated to constant trimming, and practicing flying with their model's precise maneuvers. It seems to me scale contests are made to reward people that have spent their time researching, building, and detailing their models, then flying them.

And I agree with the lame lack of time excuse - everyone gets 24 hours in a day, no more, no less.

Those are my opinions, however flawed they may appear!