The Olympics, at Stratford, had the significant advantage of being adjacent to the best transport hub in East London. As well as the Javelin, there were two high capacity tube lines which ran at 30tph, 2 DLR lines at 10-15tph, and the Great Eastern line from central London at 14tph minimum. Collectively, capacity for well over 50,000 people per hour from Central London. That’s not including the District / H&C / c2c lines to West Ham which were also pushed as routes to Stratford, nor the North London Line. All with general advice for non Olympics travellers to avoid if possible.
The London resort has, in normal circumstances, 4tph from London to Ebbsfleet, and 4tph from London to Swanscombe. About 10% of the capacity to Stratford. And that’s before the point of the issue - the London resort don’t want to spend money on the stations, and suggest everyone using rail will rock up at Ebbsfleet rather than Swnscombe. Clearly that’s not the case.