1. If you read enough, (spaced) repetition occurs naturally. No need for a software.

2. It's not bad to forget words during the learning process.

3. Purely personal: SRS reviewing is the ultimate bore, however you design your cards. And making the cards is even more of a bore. It's the opposite of fun.

It's good for 'grinding it out' type learning tasks. Example: I sat for and passed all three ham radio exams in one shot mainly because of an android ham radio exam prep app that did SRS. No way I could have done that just by reading ham radio study guides.

This thread is living proof why many people are seemingly unable to learn languages (well): they're more concerned with tools and methodologies instead of simply putting in the effort and learning the language they want to learn (emphasis on "want to learn"). Yes, it's (sometimes hard) work to learn a language and there is no magical fairy dust.

The top comment is from someone who put 370 days straight into Duolingo and completed the content for multiple languages. Is that indicative of someone unwilling to "simply [put] in the effort"?

Yes, straight into Duolingo. A tool. A gimmick. And the results were, according to the commenter, underwhelming. But I can tell you what I mean by putting in the effort: I had to learn Classical Latin and pass an exam in order to enrol in University in Germany. For that I took a two-month crash course.

What did we do in this course? 4 weeks of grammar, interspersed with reading, analyzing and translating classical texts, then 4 weeks of reading, analyzing and translating classical texts. 4 hours in class plus 2-4 hours self-study each day. It worked like a charm. The bottom line: if your aim is to read classical texts, read classical texts. And the key here was not that I learned 4-8 hours each day, the key was that the learning was not dumbed down, gamified, artificially made fun. And I have found that this is applicable to pretty much every other language.