Well, not really.

I don't think 1000dT J1 & J2 Merchants w/ over 500t of cargo actually qualify as 'tramps' esp not if operated by MegaCorps!
Ditto for same size 'Liners' which can carry, in addition to their passengers, cargo from <100t to >200t.

Those can easily satisfy trade volume requirements.

DGP's 'late-comer' vision of highly specialized worlds dependant upon massive bulk carriers is not necessary although it did help explain how so many worlds folded up like wet tissue paper when the big crunch came.
But it wasn't in CT & CT was just fine.

And now it appears that T5 has swung the pendulum way, way towards the low-end.

Seems to me that that implies it has MM's endorsement.
Which hardly seems surprising as he set up CT originally.

--------------------------------------------------------------------------------------------
On Sun, 8/24/14, Craig Berry <xxxxxx@gmail.com> wrote:

 Subject: Re: [TML] expected ship traffic
 To: xxxxxx@simplelists.com
 Date: Sunday, August 24, 2014, 3:49 PM

 There are
 two extremes. In one case, where resources and tech are
 unevenly distributed and shipping is dirt cheap, it makes
 sense to ship a million tons of gravel from world A to world
 B if the kind of gravel needed is 5% cheaper on world A. At
 the other, where nanobots can replicate anything, or
 shipping is very expensive, only rare, perhaps even
 one-of-a-kind art objects and the like would routinely be
 shipped; everything else would be transmitted as information
 and synthesized at the destination.

 Traveller in all its
 incarnations has been somewhere in the middle. Worlds are
 quite different in both resources and technology, and
 shipping is cheap enough to make trade in
 moderately-high-value commodities viable -- not quite
 gravel, but e.g. bulk food products and the like. The only
 dilemma is that some versions have suggested that only
 "tramp steamers" provide freight service, when in
 any economically reasonable model, such a situation would
 certainly lead to large-scale container freight service
 between nearby high-trade worlds.

 If you want to keep the
 "tramp steamers only" atmosphere without radically
 changing the Traveller background, you have to either
 deliberately ignore how business and economics work, or come
 up with some in-universe force opposing economies of scale
 in trade (e.g., outright regulation by the Imperium).
 It's possible to imagine such a scenario, but quite a
 stretch; some very politically powerful interests (various
 megacorps and nobles) would fight very, very hard against
 such regulations. And it's hard to imagine who would be
 fighting with equal passion and political leverage to retain
 them.