There is not enough info in your OP to say... Maybe if they have never tried and the child doesn't have any medical or aln issues which would mean parents know that are not ready, then yes, but I think that's rarely the case.
Mine were both in nappies until 3 and some months, despite trying sooner, so only a matter of months off what you would call neglectful. I'm not sure why it would have been less neglectful to let them have loads of accidents and a lot of stress than leave it a few months and try again? And why is 4 your magic number? Is that based on any medical evidence or child development research?
And are you talking about daytime? Because my daughter was in nappies at night until older than 4, as was my nephew. Every medical piece of advice i could find was that it was 'normal' until 7 and there isn't much you could do to train, there are biological processes involved in waking when you need the toilet, and some children take longer than others. Certainly my son became dry at night naturally straight after being dry in the day with little effort by us to night train him that soon, so that convinced me kids are just different...
And also, many additional learning needs and neuro diversities are not diagnosed until later than 4 in most kids, if ever, so I don't think those saying it depends if they have disabilities can be so clear cut... At that age it's more useful to accept everyone is different than put a black and white label on it in my experience.
I suspect your post had made a lot of people feels shit, and given you haven't been back to clarify context or answer some of the points made, maybe that was your intention, I don't know.