Does the age factor counts to get a job, say if some one is around 70 , what are the chances to qualify?

Age factor has a good factor to be effective in work it means the more he is older to his profession the more he is effective to his work why because he encountered many different problems and yet he still in his profession like a doctor the more he practise his profession the more he become strong 

In my oppinion it does effect to qualify a job.