The statement contrasts the attitude of "the philosophers" with the attitude of "the romantics." If the writer had meant to refer to the attitude of the philosophers who were contemporary with the romantics, the verb would have been regarded. Obviously, during the Romantic movement, there were philosophers, but the writer didn't mean to refer to those philosophers who were active at the same time as the Romantic movement.
The writer was contrasting the romantics' attitude with a philosophy, a view of human feelings, that was already established. The writer was depicting "the philosophers'" view of human feelings as having come into existence and become prevalent prior to the rise of the Romantic movement.
Can it refer to feelings? The singular pronoun it should not be used to refer to a plural noun. Many writers, however, forget this rule, and use pronouns and even verbs that do not agree in number with their antecedents. The writer may have been influenced by the use of the singular noun obstacle, which occurs closer to the pronoun than the true antecedent, feelings. The principle underlying this use of a number marking that agrees with the closest noun rather than with the true antecedent is called "proximity." Such lack of number agreement is quite widespread, even though it is not grammatical.