system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] How powerful was old Obi-Wan?

Using Yoda as an example, he was extremely powerful despite his advanced age (although Yoda may be an exception because of his incredible knowledge of the force), was Obi-Wan more powerful when he was older? 

Did he gain any power during the years between Episodes 3 and 4 besides the ability to become a force ghost?

Would he have been able to defeat Vader if he had not allowed himself to be killed? Since Vaders robotics weakened his connection with the force would he still have been able to defeat Obi-Wan?

Was the plan for Obi-Wan to die the whole time and come back as a force ghost to help Luke in the grand scheme to overthrow The Emperor?
gpt
The theory is that Obi-Wan, having lost his own master right before his eyes years ago, understood the impact his death would have on Luke all that much more. He did not needlessly sacrificed himself as an unnecessary distraction (because the Empire intended to allow the Falcon's escape all along) but rather to galvanize the younger Skywalker onto the path of the Force and into destroying the Death Star.