Considering that the Big Bang is supposed to start in a singularity consisting of all the mass in the universe I would think that implies a black hole. Current theories for early post Bang time involves the creation of black holes ranging from quantum sizes to galactic sizes. No black holes would change the dynamics and evolution of the early universe. If the early universe proceeded differently than thought then intermediate events would need to be different to still end with the current visible universe.
A Sci Fi author (
James P. Hogan) made a point about the big bang once. He pointed out that if you try and predict the behaviour of matter based on a limited range of conditions you will extrapolate wrongly. Water for example, study it at 1g and 1 atmosphere and between 50
oF and 150
oF and you will not extrapolate the boiling point, maximum density down around 40
oF and solidifying at 32
oF. He pointed out that phase changes occur where the rules change. Extrapolating backwards without limit you may reach a set of conditions where a phase change occurs and the rules change. If you miss understanding something such as black holes then your extrapolation will be wrong.
If MECOs replace black holes then early conditions would be different and driven by different forces perhaps implying such a phase change as Hogan suggests. Galactic cores would be different with powerful magnetic forces rather than just gravitational. Even solar gravity would be somewhat different if the core reaches a maximum density as a magnetic plasma instead of degenerate matter and that density is lower and exists over a larger volume with magnetic forces reaching out to affect even more mass. It might even explain why sustained fusion isn't working as wished.
If MECOs replace black holes what about neutron stars and pulsars? If
they don't exist then the mechanisms of Novae may also have been wrong.
Proving the MECO would result in reexamining a vast amount of physics and cosmology. Just as relativity and quantum mechanics has. A change such as this tends to cascade into other areas.