guess what time is peak time?
It's not as simple as that these days.
There's peak demand, countrywide, which as you say is typically winter teatime.
There's also lowest capacity margin (demand vs supply), and that's when electricity on the 'spot' market is going to be most expensive. *nobody* knows ahead of time when that is going to be.
" It saves the power companies from having to build infrastructure to handle peak demand."
Right. Why invest when there's no penalty for not investing, and it's more profitable this year and next if they *don't* invest??
"The dimbulbs that come up with these schemes seem to rarely think through all the consequences."
Quite. GWh means GWh, and so the price per GWh is the same, whether it's a soft GWh (might or might not be there when you need it, e.g. wind/solar) or a hard GWh which generally will be there when you need it (nuclear, hydro, arguably fossil). Makes perfect sense. To the beancounters.