They do have limits which you have to ask to remove. For example, you are limited to 5 elastic IPs per region. We had to ask to get that limitation removed and explain why we felt that we needed more EIPS.
If I recall, we were also limited to (10?) instances and had to ask for more and explain why.
The requirement to explain why you need additional IP addresses likely just flows out of ARIN rules that say ISPs must be able to prove their customers are using addresses efficiently and with justification.
If I recall, we were also limited to (10?) instances and had to ask for more and explain why.
It took a few days to get approved.