By 6 April 1941, the Germans had a plan for occupying Yugoslavia, That allowed the Germans to fix the invasion of Russia as 22 June 1941. They now had 17 armored divisions and 106 non-armored divisions for the Russian operation. The countries subservient to Germany also had deployed their units for the Russian operation.
The Greek General Papagos believed that the British should focus on taking Libya rather than defending Greece. The British General O'Connor had thought he could have captured Tripoli if he had not been stopped and the units sent to Greece.
By the time that the Greek government had accepted British aid in defending Greece, the British army in North Africa was withdrawing from Rommel's advance to the East.
The Australian General wrote that ignoring military considerations because of political factors was asking for trouble, as the outcome in Greece showed. The outcome in Greece was pre-determined due to wishful thinking and ignoring real military considerations. As we have seen, the motivation for the Greek operation was strictly political.
General Dill, the CIGS, General Wavell, and Admiral Cunningham all realized that the chances of success on Greece were small. They went ahead with the operation because they knew that they were expected to make the effort.
This is based on the account in "Greece, Crete, and Syria" by Gavin Long.