OP - you said But I still don't agree convenience is a valid argument. can I ask why not? Why is "I have limited time so I buy products that reduce the amount of time and effort I have to put into certain tasks" not valid? Why is not wanting to waste my time not something that's acceptable to you?
I don't have a lot of spare time, perhaps you do so you don't value time and effort in the same way.
Personally, I'll use things that make my life easier and reduce the amount of my limited time on this earth doing dull mundane things. If I use disposable nappies, I just take one off DD, stick it in the bin and put a clean one on her. I don't have to put any more effort in than that, I don't have to carry a selection of dirty nappies around with me for hours, I don't have to store them at home until I have a machine load full of them, put the machine on, put them in the tumble dryer. I just about manage to do one wash load of clothes a day for us, ifI have to factor in washing and drying nappies, that's going to eat into my time.
Same argument for reusable vs disposable saintary wear, with the added issues of a) I don't always know when my period's going to start, if I get caught out by a day, there's always somewhere close by I can quickly buy a pack of dispoable pads and b) the reusable ones my friends use are very thick - and will show through tight clothing. (as well as being less comfortable than disposable, and no, I don't care if you think I should have an uncomfy foff for the environment.)
I use loo roll that's on offer, I don't care if it's recycled or not, I use baby wipes because I can't be arsed carrying around several flannels to wipe Dd with.
I don't think it's healthy to keep holding a baby over a toilet, and again, I've got better things to do with my time.
My time on earth is limited, the earth's resources are limited. Of those two limited things, i value my time higher, you don't, that's great, I think you are wrong but it's your choice.