given that Mongoose can pretty well be summed up as 'it's MegaTraveller, but it's not broken'. (I've used this descriptor to a couple handfuls of 'back in the day' fatbeards and every last one of them groked it)
not really hating, but the similarities are marked and MT's ease-of-use is substantially better.
The problem being that making the claim is making a flagrantly false claim.
They set out with similar goals, but took VERY different directions from CT.
MT adds one roll and 0-3 skills per term to basic gen characters, and increases skill choices in all careers via use of CT-style cascades, and rolls weapons into a smaller number of much broader skills. It uses a variant on Striker, and simply changes HG to use the task system (disrupting the chances a bit, tho'). Craft design is rooted in striker, and merged with Bk5 design; the jump fuel changes were based upon the inability to make reasonable fuel levels practical due to significantly higher striker fuel rates for fusion. (TNE solved this by rescaling the use numbers, but using the same numbers.
MT Suffers badly from massive errata (Don's is comprehensive, but lots of them are trivial), and the excellent combat system was very poorly worded, the HG variant was out of synch with the rest of the mechanics, and core rules vol 4 was not in the core box.
MGT suffers from not being actually the same skill list as CT, using T5's ACS in simplification but based upon an early draft, a much LESS flexible task system than the DGP one, a combat system that (while simple) makes armor almost too valuable (Battle Dress is almost proof against a body pistol - which is essentially, a .22 cal, like a Jennings - and when it does get through it, it does very little - when realistically, if you're in battle dress, and get shot with a .22, either it should be doing full damage because it missed all the hard parts, or bouncing. Plus, the rules for larger ships are needlessly convoluted, resulting in not fixing the CT complaint of "two different design systems - one for small ships, another for big ones" - a complaint which lead many Refs to pick one or the other, and forbid mixed designs. And while a deckplan for every ship in the adventure class ships range is a laudable approach, but do we really need nearly unreadable deckplans for the Tigress?
They are as different as night and day - where MT took one approach, almost case by case, Gareth chose to go the other direction.
MT was an evolution with typsetting issues.
MGT is a redesign from first principles and ignoring the 20 years of post-CT development in the line.