The phrase "are equally necessary" is correct and usable in written English.
It can be used when discussing the importance or requirement of multiple elements being the same in terms of necessity.
Example: "In this project, both creativity and technical skills are equally necessary for success."
Alternatives: "are just as essential" or "are of equal importance".
Still, while distinct, both elements are equally necessary to being a human being.
For example, Harvard's renowned professor of Psychology Steven Pinker reports that "People somehow distinguish just one of the necessary conditions for an event as its cause and the others as mere enablers or helpers, even when all are equally necessary" (Pinker 2007, 214).
In other words, the labor migration that allows people in poorer countries to support seniors economically simultaneously threatens the human support systems that are equally necessary. .
Though identifying tradeoffs is important, strategies to minimize it are equally necessary.
Both core and attachment proteins are equally necessary for complexes to function.
Other incentive and financing mechanisms to stimulate research and development of new products are equally necessary, along with complementary measures to promote access.
An ability to draw out all the psychological and emotional dimensions of the characters is equally necessary, and by these criteria the performances were sometimes disappointing.
So I'm guessing that the iPhone's upsizing will be equally necessary to accommodate a bigger battery, so that Apple can solve the 4G/dead battery issue.
Though the first collection might be more consistent — it was short-listed for a National Book Award, but it is still under-read — this one is equally necessary for its occasional missteps.
Finally, we act teleologically (= directed towards a purpose) which is equally necessary in order to reach a goal.
Monitoring of water quality of reclaimed water and water reclamation sources is equally necessary to design the most adequate treatment procedures aimed to water reuse for different needs.
