"merely focusing on" is a correct and usable part of a sentence in written English.
You would use it to describe a person or action that is only focusing on a limited area or subject, and possibly overlooking other aspects that are relevant. For example, "The teacher was merely focusing on math without considering other important subjects like English and science."
Merely focusing on developing and training one aspect of our brains creates disconnected knowledge that lies miles from being creative and cultivating new thoughts.
Rather than merely focusing on gender and race (as it was accused of), it sought to tackle other areas of inequality related to class and age discrimination.
"We need to decide whether we're merely focusing on these two games or looking further into the future and exposing other players.
Reading Pacific Time's menu — or, for that matter, merely focusing on its name — provokes some cognitive dissonance, in that the restaurant looks to countries on the big ocean that Miami is nowhere near.
Available from Friday UnStyled Refinery29's latest podcast does something you might not expect a New York-based "lifestyle" publisher to do: offering honest advice and anecdotes on personal style, rather than merely focusing on current trends.
It seems that merely focusing on the subpopulation of divorced couples and ignoring those who might divorce in the future may cause selection bias.
He is merely focused on one last campaign and he does not think that his players will be adversely affected by him serving notice of his intentions.
Studies that merely focused on one-dimensional aspects of HRQoL such as fatigue, anxiety or depression were excluded from this review because this is not consistent with the multidimensional concept of HRQoL (i.e. the existential influence of disease on physical, emotional and social functioning).
A comprehensive theory of wartime justice must include consideration of them, and not merely focus on what one may do to the enemy.
Walk advises that strategy will build a stronger company over time than one which merely focuses on skills.
Although collaborations with private parties outside the municipal organisation (such as sports clubs or housing corporations) are very common and can also have beneficial effects on the integrated approach of stimulating physical activity, this was not taken into account; the policy analysis merely focuses on policy initiatives that involved more than one municipal policy sector.
