Unnecessary "of" ?

[pdh0224]

Dear teacher,

He continued, "They are thought of as a subtle form of deception - both unethical and potentially creating a small risk of a malpractice suit."


Q : Why is "of" used in the sentence? I think it is unnecessary

because just using "thought" makes sense in the sentence.

What do you think?



All the best, :)

[Alan]

'Of' is needed here, since this represents the active construction 'think Of smth. as...'.