Here is the idea, let say I have 2 websites that have different location of target visitors, for e.g: Website A is intended for visitors from South East Asia, and Website B intended for visitors from Central America, as you know there are timezone different approx 12 hours..

Note: Both websites has a quite huge visitors >5,000/day. And let say I have server DO with 2 GB RAM already that cost $34/month. Rather than buy another server 2 GB RAM, I would prefer to buy additional IP address that might cost me $2/month. and I would not bother with the server load issue, since the peak time for those 2 servers must be different, while on the night on south east asia, visitors from central america will get the 2GB ram allocation and while midnight on central america, visitors from south east asia will get 2GB ram allocation too.

I know vultr, linode and probably the others provide the additional IP address.

hope this makes sense, Cheers :)