Buying a house costs so much money and time that most people .... Suggesting FOSS to replace “whatever commercial software they use” is the polar opposite, in that it’s literally free
Suggesting people 'just' buy a house is unhelpful, because it assumes they have enough money to do so.
Suggesting people 'just' use FOSS is often unhelpful, because it assumes they have sufficient computer abilities and/or have the time to learn how.
Some kid who's just started writing his thesis and enjoys fiddling with stuff? Sure, recommend LaTex.
Some overstretched parent of two, who gets home at 8 and just needs to edit a powerpoint for a presentation at the end of the week? No, suggesting they install a piece of software, something they've never done before, and learn to use this piece of software they've never used, to finish something that needs to be done by the end of the night, and that they're almost certainly going to be using in an office (ie. windows/office) environment? Not helpful.