The person who stated this seems to prioritize fluency of reading over accuracy of reading. Indeed, skimming to grasp the big picture is a crucial skill and dwelling on a specific word can slow down the speed. It's no big deal to skip just a few uncertain words since the context can still support one's understanding of the text. However, this can only be viable when one understands over 70 percent of the text. Too much ambiguity will hinder his/her comprehension.
Before reaching level of CEFR B2, I'm afraid explicit teaching\memorization of vocabulary is still an inevitable learning process. After all, establishing a good fundation of English lexicon in the studetns can send them walk easier and farther in later education or employment.