No going off-grid is a substantially larger investment than most people can afford. To be off grid you have to be able to make enough electricity even on cloudy, short winter days. That means your system must be massively oversized for your needs during most of the year. You also need adequate batteries to store energy for overnight.

Instead people get enough solar to offset some or all of the electricity they use - but on average over time. So they produce a ton during the day and then draw from grid at night.

That is not the point. Solar provides most of your power and if you need additional power you can easily get additional power from the grid. That power can come from other people that have solar connected to the grid or other sources. It allows people to not have to spend huge amounts of money on batteries while providing power for themselves and others.