The 2× recommendation is indeed way old, it stems from a time when computers had 1 or 2 GB of RAM or even less. Nowadays, if you have 16GB of RAM I’d say you’re not going to need it (in most use cases).
Chances are your RAM will rarely get so full that your system will need to swap to disk, it’s probably going to clear buffer/cached data first. This is data kept in RAM that’s not actively used by the system but might be useful soon.
If your RAM does run full you either have some very specific application that demands it (then you probably already know the importance and hopefully wouldn’t ask internet randos) or you have a memory leak - that’s a problem and I don’t believe swapping helps in this case. It’s way too slow for that.
If you run VMs and reserve RAM for each those considerations might change.
Personally I don’t think swap partitions are particularly useful any more, certainly not 2× your RAM. If you ever want to suspend your system, then it needs to store all your RAM content to disk and it will use your swap for it, so 1× your RAM would be required. But with modern systems and SSDs booting only takes seconds, so I don’t think suspend to disk has much utility.
For me swap files are a good compromise. But if a system with 16GB starts swapping, something is not going well.