I'm not saying it would do away with the pyramid, I'm just saying you'd get more Refinements to throw around in exchange for loss of versatility.
This mostly came about because being forced to play a "focused practitioner" as only being good at pyromancy when in fact they had like +3 power and control to geomancy was starting to annoy me.
I crunched some numbers on this, and you never really seem to gain more than a shift or two towards your "focus" versus just having a full pyramid. Take a look at the specialization pyramid of Crash Burntown, pyromancer, who's spent 8 Refinements.
+1 Earth Control, +2 Spirit Power, +3 Spirit Control, +4 Fire Control, +5 Fire Power
He's got half a Refinement left, which he presumably puts into a focus item or an enchanted item. Whatever. Now, Mr. Burntown takes the Power, and subsequently gains 10 Refinements for the price of 8 in exchange for being terrible at everything that isn't fire magic. His pyramid looks like this.
+1---, +2---, +3---, +4---, +5 Fire Control, +6 Fire Power
He has two Refinements left over, which he presumably puts into focus or enchanted items. Crash is now a much stronger pyromancer, at the price of only being good at pyromancy.
Also, I just realized there's at least one character in the series who becomes much easier to model if this power exists- Mortimer Lindquist. He has Ritual:Ectomancy in pretty much all his writeups, which is straight up worse than just Thaumaturgy, but he's repeatedly described as stomping all over Harry when it comes to his area of expertise.