Tricky "it is at least another pair of hands. Someone to may be do the shopping, change a nappy once in a while, cook the dinner, wash up, take the baby/child from you in the evening etc."
That argument holds if they do actually do any of those things. My XH worked shifts so was rarely around at weekends, often working until late in the evenings and his random hours meant that I never got into a routine. He wouldn't get up in the night because his 'oh so important' job meant that he needed to be well rested, so I had to silence the babies as soon as they stirred to prevent waking him.
He rarely cooked a meal in 15 years, made cups of tea yes, but he didn't clean, tidy or do any housework, go to the supermarket or pick up food on his way home. He would sometimes take the washing out of the machine and leave it in the basket drying so I had to hang it out straight away, whereas I would have left it until convenient, so even his 'helping' didn't make my life any easier.
I used to dread him coming though the door in the evening, wondering what I had been doing all day because the house was in 'such a state' after the DCs and I had spent a frantic half hour tidying up to try to prevent any stress for him. I would have prepared dinner to be ready, not for the minute he came in because that would stress him out, but for approximately 15 minutes later to give him time to get changed and wind down. It was a big juggling act of trying to make sure everything was ok for him.
I always thought that I was basically a single parent, but with the added stress of someone else to take care of, with impossibly high standards and emotional abuse thrown in for good measure.
Now that I am on my own with 3 DCs I can confirm that life is actually easier without that tosspot around! However, I never had to experience it with a newborn baby, so I'm sure you are finding it much tougher than many.
I would try and console yourself that the people who say that to you probably have a useless H like mine and to them, the presence of their OH doesn't make their life any easier or more pleasant, in fact they would probably be happier without them. However, it is insensitive of them to try and make you feel like it doesn't make a difference to YOU.
As Orchard says too "I now have a dp who doesn't even live here but the difference in how I feel just because I have someone to talk to at the end of a bad day and someone that can give you a 'man-hug' and that makes you feel like you're part of a team is crazy ."
When you don't have that, it does seem that being on your own isn't that different.