proposal to provoke heated discussion

Hello
I have long felt that the best way to lower the cost to orbit is to
construct a ground based launch system that can accomodate most
existing launch vehicles. I mean some sort of launch rail system that
either via EM or jets or rockets or rubber bands can accelerate a
launch vehicle to near escape velocity.

Hear me out. Such a system would be complex and costly but none of it
would have to be flight worthy so steel and concrete could be used.
Development would be simplified since failures could be repaired or
modified rather than exploding and requiring a new launcher as a new
rocket would require.

What do you think?