I'm a vegetarian, and have been for (what?) a year or two. Not for health reasons, or ecological ones, but for ethical and religious reasons. More about that later, maybe.
And when you read personal narratives of vegetarianism, there comes that assumption that there must be a reason, other than simply not liking to eat meat. There has to be some higher purpose, as if the cuisine isn't enough. It's not just a diet, but a diet that calls for an apologia and even a meta-narrative. Others do this -- oh, ye paleo or raw food people -- but most people don't, and probably wonder why. And as someone who used to make wicked jokes about vegetarianism, I know that "eating on purpose" can be annoying.
But here's the thing. All else being true, it's cheaper (overall) to be a vegetarian, and especially about a century or more ago when vegetarians were organizing into groups. Meat was expensive -- heck! food was expensive. So for some diners -- this is where proper history helps -- simple vegetarian fare was (first and foremost) affordable, served with a side of moral uplift and resolve.
Think about churches. There are true believers and people who are in vested in the institutions. The "churchiness" of it. The theology. But many will care about the stained glass or the organ. A kind word over coffee. Or learning in a class with other oddballs. "Unchurchy" reasons. One reason that you can find non-Christians in all kinds of Christian churches; a liberal approach to participation.
The secret lesson of the vegetarians is that the high -- no, not high, but particular, formal and sacrificial -- commitment approach to church life, which works for "churchy" people like me, is a turn-off for people who want to make their own experience in our shared setting. There's room for all kinds of people, including those who are "churched" for their own needs and own convenience.