Stroop theorises that the lowering ofwel open-mid to open diphthongs is a phonetically "natural" and inevitable development and that Dutch, after it had diphthongised the long high vowels like German and English, "should" have lowered the diphthongs like German and English as well. – Zakelijke Communicatie: in de internationale zakenwereld https://groenenprachtig.nl/waarom-u-een-beedigd-vertaler-nodig-hebt-voor-uw-nederlands-engelse-documenten/