I don’t think anybody on this thread has made such an argument, but I have heard a lot of arguments of the form
“How can you say language X is especially difficult. There are also difficulties in English and therefore English and language X are equally as difficult.”
Such arguments ignore all shades of grey. Of course there are major difficulties in English. After less than two years learning German, I feel like I can spell words after hearing them for the first time much better in German than in English. There are irregularities in the German spelling system, but they are not frequent and not a difficulty (see, this is where shades of grey are important). I am sure there are other major difficulties that are particular to English.
Do these difficulties exceed the difficulties in German? For me, it is hard to say since I have never learned English as a foreign language. Based on what a lot of people who have learned both say, the answer is no. It appears that German has difficulties that far exceed the difficulties in English. For example, there is the massively irregular system of German noun genders, the irregular system of German noun pluralisations, the irregular case system (a lot of people think there are standard rules for choosing between accusative and dative but I have never seen such a system that applies to more than a small number of situations), the massive number randomly reflexive verbs (and the random choice between accusative and dative for the reflexive pronouns), and the smaller number of randomly declining nouns. These are just the irregularities and it’s not until you get into the regular bits, such as the articles and the adjective declension, that the fun begins, but that’s a story for another time…
Anyway, in terms of grammar, Russian makes German look like Esperanto.