The most compelling counter is one throwaway comment I saw here - that things are just going to get so complex we will be overwhelmed with complexity and leaky abstractions and progress will crash into a wall before intelligence amplification helps us pass said wall.

I prefer the ideas of Aubrey De Gray, because while they require future-technology and future-developments, they don't require intelligence amplification or AI or thought-to-be-impossible technology, and if done successfully would give us longer lives which might be the equivalent of amplified intelligence allowing a way round said wall (i.e. work at the same level of smartness, but for longer).