Don't get us wrong. We really appreciate jinja and their aesthetic, but while jinjas are the most visible part of shintô, they are but a fraction of the cultural basis of shintô. — much like mushrooms being the obvious fruiting bodies of the much larger mass of a mostly hidden mycelium.

Jinja are a nice option to have, but with the possible exception of jinja shintô, not really necessary to the practices.

Many of the folk practices that were incorporated into minzoku shintô, originated before there were jinja. These were carried out in a grove, or on a mountain, or where the fields met the forest, or on the bank of a river or lake.

There were no buildings; just a himorogi of poles and a rope to recognize that for that moment, the sacred could manifest there.

So if you're near a jinja, great — avail yourself of what they have to offer. However, don't let the lack of one interfere with your practice.