Are those wordpress pages cached, or generated for every pageload? Because if you generate it once and then basically just serve static content, yeah that works fine on any potato (and that's how static hosting should be, so that's great)
I tried running Wordpress with some plugins that required fresh page generation for every pageload for a friend on an Intel Atom... D525 I think it was. A single pageload was more than twenty seconds if I'm not mistaken. Without looking up that model number I'd guess this Celeron probably has similar performance, so your being able to host 'multiple' of those sounds like there's more in play
If the site takes twenty seconds on a D525, it's probably pretty demanding server-side and will require solid hardware to deliver many requests at good performance. Imagine if you're using a machine twenty times faster than the D525 (i.e. a modern desktop CPU), assuming linear speedup you can generate the page in one second. That's one second per pageload per user, and that modern machine is going to likely choke up too if the site gets decent traffic.
Which sums up why wordpress blogs go down a lot when the author runs on shared hosting or a VPS and didn't care to setup caching until it literally can't handle the traffic anymore
I tried running Wordpress with some plugins that required fresh page generation for every pageload for a friend on an Intel Atom... D525 I think it was. A single pageload was more than twenty seconds if I'm not mistaken. Without looking up that model number I'd guess this Celeron probably has similar performance, so your being able to host 'multiple' of those sounds like there's more in play