feeling sorry for single children is just weird, not going to lie. I was a single child. Yes i had many boring days as a toddler. I’m not a sad adult because of that, i’m happily married and expecting my 1st soon. One of my parents passed lately, that had a much more profound impact on me than any boredom during toddlerhood. Playing by myself as a toddler fostered a lot of creativity and imagination… you need that to play by yourself after all.

Eventually my mom set up a “play date” up the street with a neighbor around my age, and that was the start of proper friendship and fun. And when i learned how to socialize and share better.

It sounds like you see many “semi-enthusiastic” parents. Children should ideally live near other children so they can make friends. Or be enrolled in some type of pre-k so they can make friends. That’s a (parent) life decision problem, not a “i have no siblings problem”. There’s also plenty of siblings who don’t get along anyway so that’s a poor reason to have a 2nd.