I have plenty of friends. But for a variety of reasons, none were well placed to be supportive with childcare in the pre school years. Mostly because they were busy with their own children.
In a total emergency, yes I could have called on someone but not for the sort of "we would love a weekend away" or "we could really use a day to paint/decorate" type thing. Because they had family support for that sort of thing and so didn't need anyone to have a reciprocal relationship with.
Now that my kids are primary aged, I do have a bit more of a village in that way but when they were under 5, it was a lot harder.
There is also a lot of serendipity with these things but people often think it's all your fault if it doesn't pan out.
Two examples - two of the families who used our nursery lived next door to each other so naturally they shared the nursery run. We didn't happen to have anyone on our road who used that nursery so we didn't. That was pure luck!
One of my friends from a baby group, her DD's best friend's mum turned out to live very close to them and be a qualified nanny so became their after school nanny and emergency childcare person more generally. My son didn't make such a convenient friendship!
All I am saying is that it's not always as easy as "make an effort" when you are the tired parent of under 5s