Earlier quoted context omitted.
That would be even worse! Can you imagine the headlines where it's a private company that tells the government what they need to buy AND sells it? Horrible conflict of interest. The best solution would be for government IT to simply be competitive with the private sector for talent acquisition. That would probably mean that most senior software engineers will end-up being above the mayor's paygrade however.
Can you imagine the scandal if you fully specified a product and they built it and it wasn't even fit for task. Your contractor says "They never said it had to fly, they just sent us 5999 pages of specs about the logo, the color of the seat, the tray-table latch mechanism, etc." You'd look even dumber because you proved you don't understand your own business. No organization should expand outside its desired core com…
Your projects will never succeed this way, but you’ll have plenty of people to blame for the failures.
Which is why it's already common for government IT projects to use a close variant of this approach, but usually separating out requirement writing to a firm notionally expert at doing that in the problem space instead of having it checked by sich a firm.