1) Perhaps on the continent that may be the case, but England does have a football culture that is very unforgiving to foreign managers, imo. The media will be hostile to anyone not English and not ready to give them a ready quip every game, the demands for instant success are much louder here in England than on the continent (barring insanity-inducing managerial climates like Italy), and the adversarial nature of the English game is unique as far as I can tell, with cooperation between and across clubs much less intensive than in places like Italy and the Netherlands. It is as unforgiving as it gets, and thus a manager who's come through all of that with a decent CV (Rafa, Poch) is a better choice on those standards, imo.
2) I read it. Fine, Ajax were unlucky in the CL. The article does however heavily gloss over their EL record: for such a talented side, they really should have gotten farther than they did, perhaps even won the thing outright at some point in the last few years. Okay, in the first two years of FdB's term they were European novices and had to restore their league record, so the EL must have seemed unappealing or unimportant to them. The last two, however? When they were experienced in Europe and could focus more on European competitions? No excuses there, imo, they did poorly. Worse sides than Ajax have gotten to the semi-finals of the Europa League.
3) After 2013-2014, I'm surprised anyone would still condone horrific defending and individual errors if it meant scoring goals at the other end. We should be looking for a manager who can both craft a steely defence and score a few goals: if De Boer can only achieve the latter by sacrificing the former, then he's clearly not very good, is he?.
4) Fair point, although again, his coaching of them does not indicate his readiness to handle both harsh conditions and high-maintenance players in bigger leagues like ours.