I used to ride a 1x5 system, that was how the bike came. The chainring teeth were unramped and there was no keeper or guard.
I think modern chains may have more lateral movement than chains of old, has anyone tested for this?

1x8 or 1x9 systems can provide enough gear range for rolling terrain without steep hills. The chainset is much lighter and cleaner with fewer dirt traps. There is nothing wrong with the concept as long as you can get it to work reliable with modern components.
Fit unramped rings, a chainkeeper device or some plastic chainring guards.