Ante Aikio’s paper on etymological nativization of Finnish loanwords in Saami (part of the 2007 collection Saami Linguistics ed. Toivonen & Nelson) mentions that a language-learning technique that some might chalk down to laziness or incorrigibility is actually recommended in pedagogical circles:
Estonian textbooks for native speakers of Finnish explicitly instruct the student to form Estonian words on the basis of their Finnish cognates by applying processes such as apocopation, syncopation, shortening of unstressed long vowels, and abolition of vowel harmony, which directly correspond to sound changes that have taken place during the history of Estonian.
For instance, Kasik’s Estonian textbook (1991) begins with a description of eight consonant and nine vowel rules by which Finnish word-forms can be regularly transformed into their Estonian cognates. After this there is an exercise where the student must convert entire Finnish sentences into Estonian by applying these rules:
Finnish Minä olen uusi eestin kielen opettaja. Estonian Mina olen uus eesti keele õpetaja. English “I am the new Estonian teacher”
The rules applied include abolition of vowel harmony (minä > mina), apocope after a long initial syllable (uusi > uus), deletion of the genitive singular ending -n (eestin kielen > eesti keele), monophthongization of falling diphthongs (kielen > keele), the vowel shift o > õ, and the shortening of geminates in suffixal syllables (opettaja > õpetaja).
It would be interesting to collect the opinions of some Estonians on this. My bilingual Russian–Polish wife is exasperated that I’ve gradually learned Polish by thinking in Russian and then changing each of the words as needed (as her Muscovite mother did before her). Are Estonians similarly annoyed by Finns treating their language as a variant of Finnish instead of learning it bottom-up on its own terms?