I think whether it is a religion or not depends on your view of religion vs what it has been vs what it could be.
When James and Paul got into a argument over faith vs works James said I show you my faith by works.
In a similar fashion religion is "the works" of spirituality. Do you need a religion to be spiritual? No. Religions tend to be institutions... organizations... they take this name/title but isn't the same as you, the individual, having religion. And because many people rebel against these institutions that's how we get so many people claiming to be spiritual rather than religious. And this can also mean that a person thinks and believes but doesn't have any identifiable religious practices. As religion is defined as beliefs and practices.
Practices can enhance the belief. The point of it is reinforcement.
Rastafarianism is similar in ways with Jediism which is why I identify with both. And many Jedi are also members of different other religions, including Christianity. I think it is healthier to see these things as fluid instead of static so that we can continue to grow without being trapped, like certain faiths, who are trapped in a certain time period, some even refusing to use electricity.
Newer religions tend be more about freedom while older ones were more about restriction. Don't do this. Don't do that. This was the main thing Jesus dealt with in Judaism before Christianity was vomited out of it. The older heads couldn't give up Moses and his restrictions while the new followers were energized by the idea of love being the guiding principle.
So instead of defining Rastafarians by restrictions, what you have is as it should be. Different Rastas encouraging different things that you can incorporate into your personalized spiritual path and lifestyle, without it being a mandate forced upon everyone. Everyone isn't the same or has the same experiences. Some people can't even smoke the herb because it causes them to vomit. Some view it as unhealthy. Some are vegetarian. Some are vegan. Finding your own path is what spirituality is all about. No one else can give you that according to you specific needs and nature. And just because people do all these different things doesn't mean their spiritual. The spiritual benefit is not the action but what you personal get from the action.
For example... I've never felt drawn to being a vegetarian even though I was raised that way as a Christian. It seemed like an unnecessary restriction to me because Jesus and his disciples could not have been vegetarian, nor could any Israelite because they all had to eat the Passover lamb. So even if they wanted to, they couldn't avoid eating meat and keep the feast days. And I can take restrictions. That's not the problem. I just want there to be a real tangible point. Nature isn't vegetarian. Some animals are. Many aren't. It's just a matter of the needs of each species. Humans are even different from other humans. Some need more protein. Some are allergic. There is no one size fits all.
When we, as humans, try these one size fits all approaches, that's when we become intolerant to those who are different and eventually those who are different inevitably rebel against that singular order. Wars between brothers. Wars between families. Wars between nations. So if you ask me, having an individualized approach within the context of religions that are more like open-source ways of life and/or schools of thought, that accept and do not dictate spirituality... it is the biggest competition to the old world, old school religions because it has the potential to bring harmony and healing to the world.