YABU OP. Some women might enjoy visitors straight after they give birth, good for them. Others don't and shouldn't be judged for it.
Some might have had difficult pregnancies and are physically exhausted/emotionally drained and need time.
Some might have went through fertility struggles or previous losses that others don't necessarily know about, and just want to enjoy being with their precious newborn without interruption, not having to deal with selfish visitors that just want to selfishly hold the baby all the time and refuse to give it back to the mother, even when the baby is screaming because it's hungry or it's had enough of being passed around.
Others might have had long, complicated labours and are left exhausted, in pain, may have undergone surgery and just want to be given time to recover without putting up with over excited visitors that don't give a fuck about how the mother might be feeling, because they just want to see the baby for their own satisfaction.
Others might just want their mums and partners and no-one else at first just because, and don't have to go about justifying this to the in-laws or friends or work colleagues.
Others might just want to be able to sit sprawled out half naked with their babies attached to their boobs in their own living rooms without having to either a) have everyone and their granny see them in such an undignified state or, b) have to retreat to their bedrooms when they rather wouldn't so as to get some privacy to sit half naked with the boobs and everything else out because the visitors don't take the hint.
Some don't want the unsolicited "advice" people seem to freely give out as soon as a new baby is born. Let's face it, it's tiring pretending to be polite the best of times when others go about telling you what to do, or how you are doing wrong. And since the guests run the risk of being told to F-off, they might be asked to not visit at first for their own good.
Others want to learn to breastfeed without the intrusion, oggling, embarrassment, being told to FF or that the baby is starving, or the mother being told she is selfish for not letting others feed the baby.
And then there are those introverted souls that find unsolicited company draining the best of times, and just want to be left the fuck alone for a bit without having to justify their decision.