Why advocate against if in a situation where there is no other option?
Because in MA, "We try and discourage people from self help."...
In Massachusetts a private person may lawfully arrest someone who has in fact committed a felony. Commonwealth v. Lussier, 333 Mass. 83 , 92 (1955). The stricter requirement for a citizen's arrest -- that the person arrested be shown in fact to have committed a felony -- is designed to discourage such arrests and to prevent "the dangers of uncontrolled vigilantism and anarchistic actions." Commonwealth v. Klein, 372 Mass. 823 , 829 (1977). Cf. Commonwealth v. Mahnke, 368 Mass. 662 , 688-689 (1975), cert. denied, 425 U.S. 959 (1976). See also Rohan v. Sawin, 5 Cush. 281 , 285 (1851); Commonwealth v. Carey, 12 Cush. 246 , 251 (1853); Commonwealth v. Walden, 380 Mass. 724 , 728 n.2 (1980); Note, Arrest Without a Warrant in New England, 40 B.U.L. Rev. 58, 76 (1960). Generally, the person arrested must be convicted of a felony before the "in fact committed" element is satisfied and the arrest validated. If the citizen is in error in making the arrest, he may be liable in tort for false arrest or false imprisonment.
http://masscases.com/cases/app/11/11massappct165.html