Especially for indoor venues that seems completely possible.
> shoes began to incorporate air bladders and gels for cushioning
And yet springs are illegal. But an air bladder is a spring, no matter that they call it "for cushioning".
Everything that "absorbs energy and returns it" is a spring.
(I think that coming closer to a definition of spring would be "stores mechanical energy through compression and releases it through expansion").
I think that you could somewhat legitimately differentiate between an object that stores mechanical energy and releases it due to its atomic structure (ie, every object), and one which stores and releases it at an improved ratio due to macroscopic structure, such as a, well, traditional spring.
If so, one could argue they should ban those tracks, too. Modern tracks have nine lanes. The outer eight are optimized for use by sprinters, the innermost one is softer to prevent injuries to 5 and 10k runners.
That is more pronounced in gymnastics. If you held a tournament today using equipment of fifty years ago, I bet half the competitors would break a leg or an ankle.
The original olympics were conducted naked, weren't they? That's not to say that naked is the answer, but wearing cyber legs or sharkskin suits or even springy shoes would all have been off-limits thousands of years ago. Back then it was all about one human body vs. another. Back to basics, I say!