Sports do not all benefit equally from PEDs. The requirement to demonstrate high level muscular endurance over such prolonged time periods makes the relative benefits to cyclists very high.
This is different to most sports where you are less likely to grossly manipulate the factors contributing to optimal performance with PEDs. Or at least not be able to manipulate them enough to be out of range of talented non-users.
Doping can improve speed, strength, endurance, agility and recovery from training and injury. Those can be decisive advantages, even in relatively skill-based sports. They can't turn you into a top performer, but they can push you over the edge from good to great.
I think that many sports just aren't looking very hard for dopers. We know that steroid and HGH use has been rife in baseball for many years, because the MLB was forced to implement a serious testing regime after Jose Canseco blew the whistle. Golfers would likely see a similar benefit in terms of explosive power, but the PGA has the bare minimum of anti-doping controls. A suspiciously large number of golfers have returned from the winter break with an extra 15lbs of muscle and 10 yards on their drive. Soccer places high demands on aerobic endurance so players could benefit enormously from EPO use, but FIFA's testing regime is remarkably weak.
This is different to most sports where you are less likely to grossly manipulate the factors contributing to optimal performance with PEDs. Or at least not be able to manipulate them enough to be out of range of talented non-users.