Olber’s paradox does not hold as long as we admit that, observationally, there is a correlation between distance and redshift. It does not matter if the redshift is caused by expansion, or by the loss of energy of the light. The redshift will be very high before you are likely to hit a stars surface, so the brightness observed will be very low.

It also does not hold in any evolving universe, whether Big Bang or one infinitely old. In either case there will be some time before which no stars or galaxies exist. Again, you will probably go past the distance corresponding to that time long before your average sight line hits a stellar surface.

Aaron is on track that we can account for the energy inthe CMB. Jsut calculate the nergy released in creating the helium we observe and you get the right energy density and thus temperature for the CMB.