From my experience in both Development and Management in RSPS, this discussion is pretty easily squashed.
While Facebook, YouTube, Google, SEO & other means of advertisements are extremely beneficial for servers, the server has nothing to advertise on these platforms without consistent Development. Most of the time, these forms of advertisements are a HUGE waste of money, as Kris said. From RSPS Top list ads costing from $150-$600/month PER SPOT to Facebook costing depending on your outreach and audience $30-$150/month, don't get me started on RSPS YouTubers. All of these add up to an extortionate amount, when realistically, that $1000-$3000 you're spending a month on boosting your Adverstisements could go towards 1-3 Developers that will progress your server even more, and then spend $500-1000 a month on a few YouTubers/Ads to reach out and let people know about your new updates.
Main thing you need to realise is:
Can a server run without Advertisements successfully? Yes
Can a server run without Development successfully? Not a chance.
Can a server run without Management successfully? Not a chance.
However, when it comes to an RSPS first starting out, it's not what you have, it's how you portray it, and that's where advertisements and people in these management roles thrive. Maintaining a server past this point is PURELY Development priority and management, advertisements are far less-prominent when there's an existing playerbase.
Zenyte had a massive launch due to months upon months if not over a year of constant teasers, advertisements and competitions pre-launch getting everybody ready. Once they launched, they captured people who's attention hadn't been drawn through ZachTX and a few other YouTubers. Following this, they didn't use another YouTuber, no Facebook ads, no Instagram ads, only maintained their Runelocus ad-spots and being #2.
There's a reason Developers are so hard to come by these days, because people undervalue the ability they have to completely change a server, the Developers are often let down by the people who claim to be managers as they expect the server to run flawlessly as it progresses with development.
Management is so much more than advertisement as you stated, Stable. However, it has much more to do with the way you run the game and organise feedback, staff, quality assurance and development prioritisation compared to advertising. From my experience, that has been the biggest downfall of servers, and even Ataraxia at points. Developers are only as strong as the server's management, and unfortunately, we saw this with the recent downfall of Zenyte despite having Noele, Tommeh, Corey, Kris & Hacker.
OT: Have watched your recent streams, I hope you manage to find somebody, but you must value Developers a bit more, especially if you are unable to do what they do.