Achieving a new breakthrough in computing is often very expensive. Deep Blue is estimated to cost IBM over $100 million over a decade [1].
And in comparison to large tech company R&D budgets, the amount cited in the article is a drop in the bucket. Consider the fact that Google spent $26 billion in R&D budget in 2019 alone [2]. Microsoft spent almost $17 billion [3].
Did you mean to say “not everything”? Much may be, but certainly not everything. As you said, operating or maintaining software is not generally considered R&D. Development without the Research component is just Development, not Research and Development.