Most Deists would like to see Deism become as popular, if not more popular, than any major world religion or even Atheism. There is always the hope that Deism will naturally get there if circumstances change. However, pursuing that goal in a certain way can be detrimental if not outright harmful to preserving the integrity of our positions. While religions and mainstream atheism attempt to proselytize, Deists should avoid it.
This doesn't mean that you should avoid talking about Deism when the topic comes up, or refrain from educating someone unfamiliar with it. However, crossing the line into proselytizing comes with plenty of harmful effects that ought to be avoided. People are free to reason and are free to come to conclusions on their own. They may have valid and/or invalid reasons for coming to certain conclusions. It is impossible to force someone to think something. Enough force may make people put on the appearance of acceptance in public but it cannot really change their thoughts.
People are more likely to hold onto their positions, thoughts and worldview if they aren't imposed upon them. If they aren't already hostile to imposed opinions, they lack the knowledge and justification to believe imposed opinions on their own accord. While making Deism more "accessible" should always be a priority, it should not come at the cost of negating the proper method of thought to get there. It is far more valuable for someone to know about the justification for Deism and reject it than for one to be a Deist but not really know why. In most cases, the former is far more knowledgeable. Proselytizing people robs them of the chance to reason for themselves.
Another reason not to go around proselytizing for Deism is that you won't get very far with it. If you are dealing with someone likely to be proselytized by a major religion, then it is highly unlikely that what you offer will be valuable to them. If one prefers being told what to do rather than reason for themselves, then Deism cannot compete in terms of made-up answers to complex questions. Being a good philosopher requires one to be okay with the discomfort of not having instant abstractions of complicated topics. This is one barrier to entry that cannot be lowered. Nor should it be.
Proselytism is also a bad practice when engaging in debate. For starters, you should never (usually) start with the presumption that you are correct and that the opponent is wrong. It is a matter that has to be proven rather than assumed. If assumed by both parties, the possibility of valuable discourse is negated. Engaging with the assumption of being correct prior to proving it is bad faith argumentation. Not only should one not do it, but one should also avoid discourse with other parties who may engage in this negative practice as well. It cannot result in anything other than time wasted.
Given a choice between Deism becoming popular and keeping its integrity, I'm willing to bet that most Deists would pick the latter. In fact, that's probably why they aren't part of a more popular belief system. Popularity is superficial to truth, and as much as it would be an instrumentally good thing, it is not an intrinsically good thing. In trying to achieve the former, we should not sacrifice the latter. For then, we will have neither.