@QueenCold
That wasn’t performed by any single unicorn, and we have no idea how many it took then, compared to how many it would take now. We can’t compare it, because only one group did it.
That’s a societal difference, rather than a power difference. You might as well point to speaking a dead language to claim that an older group is smarter, or claiming that building the pyramids by hand instead of using construction equipment made a society more powerful.
From what we know, magic relies on knowledge and intelligence. Since modern Equestria has had more time to research magic and improve spells, they would seem to have a very important advantage, even if most unicorns no longer study magic themselves. Actually, we don’t even know how many of the ancient unicorns studied magic, so we don’t know if they had a more trained population.
Turning Day and Night seems to be everyone tier magic, along with levitation. Since everyone was able to do it, it probably wasn’t that complicated a magic.
Sidenote: I don’t have an objection to modern or ancient unicorn being more powerful, I’m just looking for a proper argument either way.