For most well-conditioned people to be able to use the bike as a viable cardio option, their legs have to make physiological changes that will negatively impact strength gains.
I have a female client who is quite strong and she has been able to add 20lbs to her 3 x 10 front squat day. Was doing 95lbs now doing 115. This change occured soon after she stopped biking for the winter.
As far as ellipticals are concerned it is more the difference between having to bear your bodyweight while exercising and the fact that the bike requires pure muscular effort, than it is the superiority of the elliptical machine over the bike. Incline walking, running, and the stairmill probably would do a much better job of burning calories than the bike for most people.
Calorie counters on cardiovascular machines are notoriously poor. Using a heart rate monitor that takes into account height, weight, gender, age and vo2 max are much better but still not perfect.