Stepping down from aluminum smelter load levels, consider the comparatively low power demands (orders of magnitude less) of modern lighting and electronics. There's some interesting geekiness to be found in their power demand under varying line voltage.

Voltage-regulated "inverter technology" electronics can, ironically, behave less "linearly" under adverse supply voltage conditions than resistive loads such as incandescent lighting and electric kettles.

Electronically-ballasted fluorescent lighting, CFLs, computer power supplies, VFD motor drives, "inverter technology" microwave ovens all electronically regulate their current draw inversely against voltage supply changes. Voltage goes down, current draw goes up, power demand remains ~relatively~ constant.

So when a brownout (voltage sag, not an outage) comes along, to some extent, these "well regulated" devices hide it from the user. You might not see a "brownout": The electronically ballasted fluorescent lights don't dim so much -- or at all --, your laptop computer keeps running fine if the sag doesn't drop too much, and any DC-powered fans won't necessarily slow down so much or at all. But maybe you heard a universal motor somewhere slowed down. Or maybe the lit-up display area on your old CRT monitor (is anyone still using those anymore?) shrinks 10% then comes back. You hear your computer's desk-side UPS click in (if it has a relay, cheap ones do) then back out but don't see the lights dim. I've seen and heard this and found it rather jarring.

The term "brownout" may become an anachronism (perhaps it has already), not because brownouts don't happen anymore, but because they don't dim the room lights anymore.

To see how much variation a small "non-dimmable" CFL will tolerate, I just put one on a variable transformer and lowered the line voltage gradually from normal (120 Volts) downward. Here's what happened: o It lost very little brightness until about 60-some Volts o Below that threshold, it just turned itself off

As a device user, this is what I'd expect of a "well-regulated" device that runs on mains (grid) power.

But I don't imagine such "well regulated" loads make grid dynamics marginally easier to control under the severe conditions which lead to voltage sags. Probably not much worse though, considering all the heavier loads a grid must support.