Why does the City of Pittsburgh not try to absorb/annex some of municipalities surrounding the city?

Pittsburgh is currently ranked the 71st largest city in the US with a population of of 302,152 and a county population of 1.238 million.

Wouldn’t annexing a majority of the smaller municipalities that are basically in city limits make sense and drive up our population

Allegheny County has 130 separate municipalities/governments and 43 public school districts.

I just don’t see how that makes sense. So many separate governments and school districts just seems like a bad idea regarding taxes, spending, infrastructure, education, budgeting??

For example I’m originally from fayette county which is a population much smaller obviously (127,244) the county has only 42 municipalities and only 8 school districts. The municipalities and school districts seems to cover much wider ranges.