Right now, top quality steel bike frames at the minimum bike weight allowed by the UCI are stronger than top quality carbon fibre bike frames of the same weight. Aluminum frames of the same weight would not be considered usable probably... (Pro cyclists would still use carbon fibre bikes because they can be made more aerodynamic).
That’s with a minimum weight imposed. Doesn’t change the fact that aluminum and titanium alloys generally have better strength-to-weight ratios than steel.