Why are there no particles that ONLY interact via the strong force?

Question

The title speaks for itself really: I noted everywhere I learned about fundamental interactions that there are particles that interact ONLY via the Weak Force (and gravity, if it counts)(e.g. neutrinos), there are some that only participate in the EM component (and gravity, if...) (e.g. photons), there are some that have no charge, but interact both with strong and weak carriers (e.g. Higgs), etc. However, it seems that no one discusses why it seems to be the case that there is not a single known particle that only interacts via the strong force.

Why do you think this is?

(NB: there also seems to be no particle that is only affected by gravity, but that is perhaps not as surprising, given that it is a very weak interaction and it would be incredibly difficult to make a detector for such a particle, unless it showed up in huge masses... perhaps dark matter?? :))

EDIT: 2023/08/16 Let me generalize the question a bit in the form of a table:

Particle	Strong	Weak	EM
gluon	X
Z, neutrinos		X
photon			X
??	X	X
W, charged leptons		X	X
??	X		X
quarks	X	X	X

Does this make more sense? Thank you for your answers.

EDIT: 2023/08/17

I would also note there is a huge difference between gluons and photons, so the table may still be a little misleading: gluons actually carry color charge, photons do not carry electric charge, so there is elementary gluon-gluon interaction, and there is only higher order (in fermion loops) interaction between photons. Similarly, W and Z do not have flavor, so also have the same note as photons. Thus the question might still include any knowledge of particles that are not affected by WI but have charge.

Answer 1

You forgot the gluons (the bosons mediating the strong interaction). They interact only via the strong force, i.e. with quarks and other gluons.

Answer 2

In grand unification theories, there is a single unified force that interacts with all the fermions. In such a theory, the forces that we know come from specific components of the unified force field, while certain other components of that unified force field become superheavy and effectively invisible. Thus, in SU(5) unified theory, we see gluons that change the color of quarks, and weak bosons that change the flavors of quarks or leptons, but e.g. we don't see the X and Y bosons that can turn a quark into a lepton.

In such a theory, the immediate answer to your question is "because the unified symmetry was broken according to a particular pattern". Going deeper might involve excursions into group theory, string theory, and the anthropic principle. However, all that would be highly speculative, since we do not even know which GUT model is correct, or indeed if any of them are correct. The same goes for any other speculative framework which proposes to explain why the known elementary particles are what they are.