Here is the issue: JB writes: "If this had not been the case, legislation like the 1986 Tax Reform Act (which overhauled the entire federal tax code), the Goldwater-Nichols bill of that year restructuring the Pentagon, and the 1990 Clean Air Act Amendments could never have been enacted." Here is the problem: all of those pieces of legislation passed with overwhelming majorities voting yes -- far more than 60 votes. For example, the Senate passed Golwater Nichols with 95 or 96 yea votes; Clean Air Act passed 89-11. Even if a few yes votes would've rather seen the bill fail, this is no way comparable to health care today. In other words, filibusters could not succeed in the Tax Reform, Goldwater-Nichols, Clean Air Act cases etc because if someone filibustered, more than 60 senators would genuinely want to end the filibuster so that the bill would pass. Today, there are not 60 senators who want the bill to pass, as it currently stands. That is lousy, but it is not something that Harry Reid could change by being a better legislative strategist. JB is right that it was not always this way: before the 1970s, it was pretty common for major, controversial bills to pass the Senate absent a filibuster-proof supportive majority. But since then, the filibuster has become so widely accepted (and so costless) that it is a real veto (except when reconciliation is an option -- which is not so feasible here) absent 60 votes. Note also: the idea of citing the southern Democrats as at all restrained on civil rights opposition is laughable. The only reason the 1964 Civil Rights Act could pass is that LBJ and the Democrats made enough concessions to Dirksen to get enough GOP votes to have 67 for cloture (which was the threshold back then). Fortunately, Dirksen was not anywhere near as conservative as today's Republicans, so the concessions were not as substantial as would be required to get GOPers on board today for any liberal legislation.
I think both readers have good points here. But, thinking back, there's no question that as recently as the 1990s filibusters (or using whatever obstructive measures to force 60 vote majorities) were much less common than they are today. Today it is treated as a given; 60 votes is the default. That simply did not used to be the case.
Some of it is a change in standards, a breakdown of informal rules, as JB suggested. But I think we're also deluding ourselves if we do not figure in a large role for larger structural changes in our politics. Simply put, the broader climate of political polarization in the country -- a socio-political reality that transcends parliamentary rules -- creates pressures for party coherence and party discipline that makes the resort to these tactics more and more the norm.