What are the Pro's of doing this?
I can clearly remember a few Con's from back in the good old days.
- 1st level PC sits in the back during any dangerous situation twidling thumbs for multiple game sessions
- Either the DM takes it easy on the new PC or he pretty much just dies to the higher level threats.
- The new PC levels up pretty fast anyway from the huge amounts of XP, so why bother.
None of those happened in my AD&D 1E, AD&D2E, BX, BECMI, nor Cyclopedia games.
Dead by area effect did happen a few times.
If they happened in yours, I suspect you need to think about the DM running them, more than the mechanics.
Now, it did happen in 3.x, that even a 3 level difference was a major problem in power level.
Then again, one or two encounters suitable for a 5th to 7th level party in AD&D or Cyclopedia would just about level up a 1st level character to 2nd... and another couple to 3rd... They'd never catch up, but they'd never stay 5-7 levels behind.
In one AD&D 2E game I ran, at one point I had a 9th level psionicist, a 6/4 Fighter-mage, a couple 7th level fighters, a 5th level thief, a 0-level PC mage (apprentice to the F-MU), an 8th level cleric, and a 1st level Flesh Golem fighter. The 0-level didn't stay that way, and was actually quite useful in combats. The 1st level fighter was soon 4th level. Yes, he was at risk. But that campaign was also largely humanoid opponents, rather than "big bad monsters", and thus his part to play wasn't hampered by being 6 levels lower than the high level fighters.
And Untie cantrips have exquisitely fun combat uses...