No, they don't say that it is meaningless. They say that if you want to break the rules, then that's fine with them, but that some of these powers aren't meant for PCs. If they didn't want to say that then they wouldn't have wasted word count on sidebar saying that.
Er, no, there's nothing in there about breaking rules or powers not being meant for PCs. As you...quoted
directly...they just note that they find it unlikely. 0 rules implementation. It's just a friendly sidebar. Doesn't even present "optional rule: this list of powers is off-limits to PCs", all it is is developer commentary.
Domination - any mortal with this power is going lawbreaker his Aspects into negative ones. That looks like NPC to me.
Greater Glamours - since full Fae lack freewill and thus are not PC types, the description is basically saying NPC only.
Your reading is off. Let's talk about that.
1) Domination does not cause Lawbreaker. It is not a Spellcasting Power. The Wardens might cite and behead you, but the universe doesn't care.
2) You may have characters which are not mortals, who do not receive the benefits or drawbacks of Lawbreaker ever.
3) You may play a Lawbreaker.
That's every angle covered on Domination, I think. No points there.
Now, Greater Glamours. Only true fae may take the power, yes. True fae don't usually have free will, ehhh...putting aside an Aspect like "Cursed With A Soul" or whatever, which is totally valid, not having free will doesn't make you "not a PC". Not having REFRESH does. A CHARACTER with no free will is not the same as a PLAYER with no free will, who may spend Fate Points (it's not a character decision, after all - you can't decide to have a fortuitous arrival or ask the universe to collapse a staircase at a dramatic moment) as usual. The PLAYER doesn't lose agency just because the CHARACTER does. For an easy example, see Harry Dresden - he's a supposedly free-willed mortal
who never resists Compels or otherwise exercises his power of choice. In nearly every situation, his reaction is predictable: he will do "the right thing" or make a grab for power to get himself closer to doing "the right thing". He never deviates. Playing a true fae is no different.
Is Greater Glamours balanced? No. Is Evocation balanced? No. Is DFRPG still awesome? Yes, so I forgive the designers their foibles.
In short: as Richard has quoted and the Powers section confirms,
nothing is barred from PC use in the rules or by implication, and author intent is clear both from the supportive text for taking whatever you feel fits your character or that you want to play with, and from the total and irrefutable lack of powers that say "PCs may not have this" or even "PCs should not have this".
The strongest language in the whole book about it is "it's
unlikely that PCs will have this". Where are you guys getting all this stuff about Domination breaks the rules or you're not supposed to make new templates even though there's a sidebar that says "if you want to, make new templates"? You have to ignore
everything to say NPC powers exist, or that the authors advocated some kind of selective one-true-wayism in the template builds. DFRPG is a permissive, open toolkit by design and by intent.