Would you also say Greek lambda has nothing to do with the English L? Or, slightly more relevant and complex example, actual Polish L with Slovak Ľ and Serbian Љ?

Conservative Ł would still be distinct.

The problem is some software just has problems with non-English alphabets because, roughly saying, all the software was meant to only process English text historically and much of it still has not been fixed. Users of non-latin-based alphabets have been accustomed to this and have no problem writing "Иван" as "Ivan" (despite it normally reads even more different in English, more correct phonetic transliteration would be "Eevan"). Heck they even spell "Семён" (~"Semyon", the Russian counterpart to English "Simon") as "Semen" X-). But the users of diacriticized Latin somehow get surprised with this.

If I could travel back in time to when ASCII was designed and give the engineers a hint I would ask them to add first-class diacritics to their design so anybody would be able to add the slash for Ł, the umlaut for Ü, Ö or whatever using an extra byte. Sadly, even today we mostly encode Ü as a letter absolutely distinct to U rather than a combination of the latter with the umlaut even though Unicode allows doing this the latter way AFAIK.