Keep in mind that a single neutron star is hard to detect, but you're talking about adding millions or billions of them to the solar system. If there were that many, it seems it'd be obvious that there were "particles" in the way of us looking at the galaxy.
I assume you mean Milky Way where you say Solar System. Obviously there's precisely zero neutron stars in the Solar System, such a presence would be easily detectable due to its gravitational influence on the Earth, moon, sun, et al.

That link just confuses me further. Honestly, I get the distinct impression that dark matter is just matter we know is there but haven't yet directly detected and classified, or profiled.

The fact we have WIMPs and MACHOs shows me that already we have two types of dark matter.

I feel like dark matter ceases to be dark matter when we see it.