Km – Reading things online doesn’t make you non-brainwashed. If does undo a good chinuch, which it sounds like you received, only to have it damaged by reading blogs from self professed academics without you yourself having the ability to look into the sources themselves.
If you want to use the term “rabbi” for anyone at any time who received smicha, then you should use it for mordechai kaplan too.
Mendelssohn wrote that tehilim is “bad poetry,” as per the actual research of rav shimon schwab, who decided to investigate mendelssohn himself, having heard different versions of his alleged personal piety.
The issue surrounding mendelssohn had little to do with secular studies, as this was common in other countries, like Italy. The issue was reform, change. He wanted to change things. He said that the Torah world needs to accommodate changing times by leaving the way we were taught. He said that mingling with non jews is good for us, against what chazal say.
His desire to abandon yiddishkeit wholesale is evidenced by his talmidim doing so very shortly after his death.
Why do i care what’s written on his matzeiva? The damage he’s done to klal yisroel is still felt today, and people who lead others astray don’t have much to worry about in terms of their matzeiva; they almost certainly won’t be needing it for its given purpose.