Because "tackling a problem" is about the approach. That's how the phrase is commonly understood. The Webster's reference is just backup. Dictionary.com provid

Because "tackling a problem" is about the approach. That's how the phrase is commonly understood. The Webster's reference is just backup. Dictionary.com provides "Make determined efforts to deal with (a problem or difficult task)." As the first verb form, before the football/rugby definition. Further, the hn guidelines suggest that even if there was more ambiguity, we should presume the strongest interpretation.