A reduction in diversity is in effect, "killing them outright". To exclude a certain set of microbes in favor of another set due to chemical inputs is in effect "killing them outright". As soil salinity rises, pH falls, soil structure changes, etc..... you get even more reductions in diversity .... once again the net effect is "killing them outright".
The statement "salt kills microbes", while grossly over generalized, is not an inaccurate statement. Likewise, the statement "salts don't kill microbes", again grossly over generalized, is not an inaccurate statement. To use one grossly over generalized statement to invalidate another grossly over generalized statement as JD does on a regular basis is simply absurd.