Unfortunately it is true. It lowers the sperm count by 1/3. If you have lot of swimmers you don't have any problems.
As someone who spent 10 years trying for children and 6 years going through IVF. I have to say that the IVF clinic disagrees with you!
I asked this specific question because I had such a low sperm count and they said if it didn't improved we may have to use donor sperm.
They said smoking cannabis does not cause an issue, smoking tobacco does, but not enough to worry about as the stress of giving up would be worse. What they told me I MUST stop was alcohol.
So I went dry for 3 months, took Well-man conception vitabiotics, zinc, iron and multi-vits, but carried on puffing like a chimney, and my sperm count improved by 50% and we now have a wonderful bouncing baby son.
I know you didn't want to swerve this thread in that direction, but as I can speak 100% from factual experience, I thought I should share this information with the community as it is important and hopefully might put others minds at ease.
If you are trying for children and having difficulties, give up the Alcohol not the dope!
Obviously if you can quit smoking and vape that'll help too, (I found vaping after the wife conceived!), but don't feel you have to quit your medicine unless it's the last resort.
As a fertility clinic that specialises in IVF including ICSI categorically told me I did not need to quit dope , just alcohol, and the results from following their advice speak for themselves.
As for the question does weed affect your sex life , for me yes, as I never smoked nor do I vape in the bedroom, so I have to pause, leave the room, have a toke, and then come back, which can be a bit of a mood killer!