This is broadly true, although in CONCACAF (or AFCON or AFC) the travel involved is often worse than Euro club and continental play.Three matches in 10 days isn’t really a problem physically. Players do three in 7-8 days all the time for their clubs, with a weekend league match, an important midweek match (often European play), then another match the following weekend.
In international soccer there is a tacit expectation (not always met) that you’re going to try to rotate some so you don’t work any one player too hard or increase their risk of injury. At the end of the day the clubs are the players’ employers, not the international associations. The clubs are allowing their very valuable employees to be effectively used for free by these other organizations. So there is some incentive not to damage the assets while you’re borrowing them if you want this arrangement to keep up. Although when national teams are desperate, they’ll overplay key players anyway.
And on the tennis v. soccer issue, it's actually an interesting question. A more-than-averagely active soccer player definitely runs more and with fewer rule-based switch-off periods. But the tennis players don't get any mental respites, because everything always rests solely on them--I think that 5-set Grand Slam play is one of the most intense athletic things you can do.
This is maybe a long way of saying that it is absolutely possible to play all 3 games in a CONCACAF window like this, but maybe not realistic to expect any but the Nadal types to play at the top of their potential in all 3.