Why doesn't ACM have a SIG for theoretical computer science?

Moshe Y. Vardi. Why doesn't ACM have a SIG for theoretical computer science?. Communications of the ACM, 58(8):5, 2015. [doi]

@article{Vardi15c,
  title = {Why doesn't ACM have a SIG for theoretical computer science?},
  author = {Moshe Y. Vardi},
  year = {2015},
  doi = {10.1145/2791388},
  url = {http://doi.acm.org/10.1145/2791388},
  researchr = {https://researchr.org/publication/Vardi15c},
  cites = {0},
  citedby = {0},
  journal = {Communications of the ACM},
  volume = {58},
  number = {8},
  pages = {5},
}