Learning and development is/are equally important

There was recently a question asking the reverse of this. If the word learning and development were used in a way that development was just another way of saying learning then the double word could be referred to with is without a problem. I do not think these two words can manage that. The key is that they must appear as one meaning.

His habit of struggling, fighting is just a way of dealing with his frustrations.

I believe if the two words are properly matched and linked with a comma then is would not be inappropriate.

When there are two abstract nouns joined by 'and' in one sentence as the subject it takes a singular verb. Look at the example below.

The batsman's caution and aggression was remarkable.