Hello John! Thank you for reaching out.
If you give the opportunity to run PHP scripts from the user Apache (nobody), then there is a high probability that your server will be subject to ddos attack. The processes that run from under the user Apache (nobody) are not placed in LVE and for them, the limits for entry processes are not considered, so these domains will be able to use all existing Apache workers, which makes it inoperative. In suexec mode, each account has its own entry processes limit, so having reached its limit, the server will continue its normal operation for the remaining accounts.