It is actually that simple. The current pricing system was created for a grid that no longer exists. There is now lots of wind generation, solar, battery power, etc. And growing rapidly. Both on the grid and domestic. And soon large amounts of batteries with wheels capable of powering houses and delivering power to the grid.

All this means lots of fluctuations in power availability and cost. Pretending that it costs the same all the time everywhere is irrational. If you give people incentives to adapt to these fluctuations, they will. Energy providers like Octopus prove that at scale. They by the way are a big proponent of more localized power. Because it's just more optimal.

Price incentives cause people and companies to adapt their behavior. Including when to to use power and where to use power. Likewise, it incentivizes power companies to invest in power generation where the demand is instead of where the NIMBY's are not (like Scottland). Speaking of NIMBY's, if they could benefit from lower pricing, they'd probably love wind power a lot more. Buy more electric cars, do the laundry when it's windy, etc.

As for base load. Nobody ever specifies a number in GW or GWH. It's a very fuzzy notion that people just assert is needed in huge (unspecified) amounts. If you put actual numbers on it, you would be able to have a sane discussion on (much) cheaper alternatives. But that never happens. Most discussions around base load center on the notion that we allegedly need a lot of it. What's the budget we need to reserve for that? How much? When? Where? Why? Are there any alternatives? The debate is mostly completely irrational and hand wavy on this.

There is a basic notion that power companies don't mind charging the same rate nationally because that means they make lots of money charging for mostly cheap power available everywhere except in a handful of places. The way the system works is that everybody pays the highest price on the system. Localized prices would introduce lots of variation and cause lots of reasons for power companies to optimize their power delivery and pricing. High prices mean unhappy customers voting with their feet. They are being shielded from that currently.

It's a big reason they are resisting changes on this front. In some cases they actually get paid to not generate power or discard it. That's wasteful. Scottland has plenty of base load. They are exporting their power surplus most of the time.