My take on it is that it's been known for a long time (1970s) that supermassive black holes couldn't possibly have been formed between the big bang and the present, never mind the early times that JWST can see into.
Astronomers will make excuses for that and say that they didn't really prove that galaxies had black holes in them and that they were really massive recently but the tension has existed for a long time because people suspected that galaxies had huge black holes but there was no path to form black holes that big.
I worked for arXiv in the 00's and had a coworker who'd gotten a PhD in astrophysics about accretion disks who was really bitter about how the poor job prospects in astronomy let senior astronomers bully junior astronomers creating a false consensus about how accretion disks and other phenomena worked. When I first heard about ΛCDM my first instinct was that some bullying was going on. [1]
Observations that the "first billion years" might have taken 10 billion years or so have been coming for a while but with JWST there is an absolute flood of them.
[1] The cold dark matter doesn't bug me half as much as the dark energy. I mean, once you look at anything bigger than a star cluster it's obvious that dark matter is there or otherwise gravity works differently in a way that is huge for objects bigger than a star cluster but doesn't show up in precision measurements at all in the solar system.
Blowtorch Theory posits that supermassive black holes formed very early, before the stars. I believe they didn't just form early, but that they were always there and the smoothness of the CMB doesn't come from natural isotropy of 'creation'. In my opinion it's so smooth because on the way to us the light was thoroughly mixed by the chaotic gravity (and now possibly electromagnetism) of all the supermassive black holes of the observable universe and the 'dust' swirling between them that were at the time that CMB light originated, crammed into a bubble of the size of merely 100 mln light-years. The relationship between CMB and supermassive blackholes exists but it's the other way around. It's not CMB that spawned black holes. It's black holes that generated the smoothness of CMB. The smoothness comes from overlapping gravitational lensing of trillion galaxies in concentrations ranging form 100 mln light years to 13 bln and acting for 13 bln years.
In my idea "Where did the supermassive black holes came from?" is the same kind of question like "Where did the universe came from?" The fact that in current Big Bang model we can imagine simple, mathematical origins (point like beginning of spacetime) doesn't make it more likely to be true. There's no doubt that Big Bang was a very energetic event, but you could get very energetic events without invoking creation. Just imagine two very dense black hole clusters, slamming into each other at relativistic speeds, each consisting of trillions (or more) of supermassive black holes.
What's great about this Blowtorch Theory is that it connects things we can actually observe, large scale structure of the universe, with the activity of those very early supermassive black holes (wherever they came from) in a measurable way thus potentially providing evidence of their very early existence. I hope it catches on because it's huge step in the right direction.
Yes, basically black holes growing speed is limited since when they eat they push away the surrounding matter so there isn't enough time. There are also no black holes in between normal size and super massive, both nearby or far away (in the past because of the speed of light)
There is the possibility that black holes larger than the usual stellar size black holes could have formed early on
https://en.wikipedia.org/wiki/Direct_collapse_black_hole
but the gap between those and supermassive black holes is huge and it is not so probable that 100 or 1000 of those would merge in the time available.
Blowtorch theory requires trillions of them
Where does it say it REQUIRES trillions? The way it reads to me, it's just associating the number of SMBHs to the number of galaxies we observe and postulates that number as a trillion, which I don't think is unreasonable given the sheer volume we see in the observable universe alone.
I was merely relaying the content of the article, I was not doubting it.