The point of sequencing is in case your preamp causes a thump when turned on.
This way I f the amp is off, the thump does not go through to the speakers.
Yes, agreed.
If your equipment doesn’t do it, then not something to worry about.
Here I disagree, because preamps can fail on startup, and especially tube preamps can send nasty noises in such an event that will reach your speakers if the amplifier is powered first.
In an unusual sloppy mood last year, I failed this best practice that I'd followed for years. That's when tubes in my ARC REF5SE blew and it shook the house. (Fortunately, no collateral damage.)