It's not a "job" in the normal sense because you're not generating profit for anyone, but the company is still paying you. All the people without children perform more labor but get rewarded less (because they get less time off, don't get whatever benefits patenthood may entail, etc.). People without children absolutely get screwed over by such arrangements.
Whether or not this is acceptable depends on your goals and what you consider acceptable incentivization schemes.
Except I'm sitting in a little room all day staring at a computer, you're spending all day with your family and seeing your new child walk and talk for the first time.
Gee, I wonder who has a more rewarding time.
New parenting (infants) is about 5% photo-filled rewarding, 95% just repetitive work, cleaning up shit (literally), waking up every couple of hours, trying to keep it together with your spouse in stressful situations with very little sleep, and feeding this organism that will eventually have a personality and start interacting back. And that ratio gradually changes as they grow older.
I remember after the first month, I used to consider going to the office my "break from parenting" because of its consistency and ability for my mind to just rest for a bit.
Just remember when you're asking a parent of an infant to have a full-time job on top of parenting, you've essentially now got an employee that is splitting their time/attention/energy between two jobs. If you're ok with the altered productivity, then that's fine.
But let's not fool ourselves.
Providing for a family is very rewarding.
The smart business move would be to let people just take the time "off" and come back healthy and rested after a few months. Not sure why businesses don't see this obvious fact.