Traveller wrote: Just look at pre-Supplement 1 OD&D, which only required a d6. When Supplement I was released, suddenly a d4, d8, d12(?), and
d20 were required to go with the d6. That is a significant addition, and is as significant an addition as
DCC requiring funky dice. Yet neither you nor I have ever played Dungeons & Dragons using only a d6.
We've never played supplementless OD&D with D6 only, because to do so would mean ditching the saving throw, contact higher plane, number appearing, % in liar tables, etc. If you lacked a D12, you wouldn't know how many mummies you've encountered.