I had the same experience, but(!) I've concluded over time that the extra "I guess", "I think", "Probably" just makes my opinions seem weaker and get disregarded. Everybody else presents their opinions as 100% fact, even when they're not sure.

I dunno if you're on the autism spectrum, I am and I think that contributes towards not wanting to write things that aren't 100% true, but I don't think it is actually a contructive thing to do since everyone implicitly understands you might be wrong.