Do I need multiple eBay accounts?

If you want to spam other power-sellers on eBay and also protect your seller account there are a couple Facebook groups you could join and become a kiss-ass to the eBay and PayPal employees that run those groups. They may allow you to spam their power sellers but I doubt it. The good thing about those two groups I know of is that if you get in good with those ambassadors and employees they let you do whatever you want on the platform, even abuse or misconduct and they won't whack your account. You may have gotten just a hint of sarcasm from me here and it's because I've written articles about this where we found that the old saying goes, "It's who you know, and who you blow" is so true when I recently found out a PayPal ambassador/employee was promoting himself on another top rated seller's YT channel using eBay employee workers to do shutouts within his video for the YouTuber which has been caught telling people to perform charge backs on people. I don't want to get into that story, and I am not going to give out the names of these groups because I am not trying to promote them. My advice would be not to spam users on eBay for you will be banned then all future accounts banned or limited as well. But I was telling the truth when I said there were a few FB Groups that you could join to get special treatment.

I am in the process now of exposing these employees on YT and over the past few days have done about 3 videos about it.

Again though, don't spam eBay users, it won't get you anywhere.