Extraordinarily disagreeing with this statement.
Skull damage currently has such a gigantic advantage over spells that it easily overcomes the highest levels of block in the game.
A meta skull crit build generates at least 2000% crit damage bonus. Even if you factor in the maximum block reduction of 80%, a player will still land a 400% crit damage bonus on any opponent that blocks. This can be achieved with a single set of gear for one character.
Conversely, spell crit damage maxes currently at just over 200%. To achieve this requires thousands of hours farming spell pages, thousands of Xione crystals consumed, and millions of spell dust all spent on raising spells on classes that a player will likely never use.
And then there’s crit chance.
Meta skull builds crit 80% of the time.
Meta spell builds crit 5% of the time.
Therefore, a skull build is 16x more likely to crit on any attack.
And then, finally, skull builds have the absolute advantage over spell builds in that skull builds leverage their weapon directly for skull damage generation, while spell builds cannot directly leverage their weapon for spell damage. At best, spell users can use the weapon effect bonus to augment spell damage (which is minor to immaterial for all weapons that can boost the spell damage formula, with the sole exception of the Dragonking Axe).
This is huge when fighting very high level opponents, because a spell build must devote at least one spell slot for damage purposes, while a skull build can devote all four spell slots for support or skull generation. As a result, skull builds have much more flexibility than spell builds by the fact that a weapon counts as a functional equivalent to fifth DPS “spell slot” that spell builds do not have access to currently.
So, no, spell builds need a LOT of love currently compared to skull builds.