I don't believe HELOCs necessarily require fees up front; that may depend on the lender. Not sure about fees to close them. To get the best rates, they do require you to borrow some money, and wait a specified amount of time to pay it back, like a 3 months, or a year or so.
So you could take out a HELOC, borrow money, and either invest it or pay it back after the initial period is over. Or you could take out a higher-rate HELOC and not actually borrow money at all. Having a HELOC isn't the same as borrowing against it.
They're not necessary. But they're nice to have as a backup, like if you need a large chunk of change for something but you don't want to sell investments and incur a greater tax burden that year. They give you greater flexibility in planning your financial strategy over a span of years.
If you don't want one, you don't need one.