Why is StreamReader Constructor (String) not following constructor instructions?

Question

Designer design guidelines ( https://msdn.microsoft.com/en-us/library/ms229060(v=vs.110).aspx ) indicates:

✓ Do minimal work in the constructor. Constructors do not have to work much, except for capturing constructor parameters. The cost of any other processing should be deferred until needed.

Constructor "public StreamReader (string path)" open the file. Is this a design mistake?

Answer 1

Is this a design mistake?

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