Yes and no. There are vegans who only eat beans, or who forego the faux meat all together because they don't care for it or are allergic. But it absolutely limits options when dining out, often to just a salad or vegetables. Most end up carrying food or simply eating before / after, but that is not an easy option on a long distance train ride. Before the advent of the faux meats it was actually easier, as many places did some type of dish that was bean based which is the least likely of the non-meat proteins to cause issues.
In the case of Amtrak, if someone is vegan AND has allergies to gluten & faux meat protein sources....it leaves nothing beyond perhaps fresh fruit at breakfast. Maybe a salad if one is lucky and croutons & cheese is packaged separately.
Even my daughter, with only a few allergies {nuts, peanut, oat, avocado and shellfish}, has minimal options for each meal. She can risk a few others given her oat issues are easily controlled & not life threatening, but it is a gamble that may make her feel bad for the rest of the trip.
It also makes me wonder - does Amtrak do anything for those requiring Kosher meals? I don't think there's anything on the menu that works with Kosher either, given the meat & dairy separation rules.
It shouldn't be difficult to allow one to uncouple the meals for medical or religious reasons.
But then again as people who know me will tell you I am not really a connoisseur of food either 
