think we’ll have to agree to disagree, i wouldn’t say it breaks a site as nothing is broken it is purely a different UX. I personally can’t stand opening a link to a different site in the same tab. I hate clicking back. With tabs i can see a new tab has opened and i can close that knowing my original starting point is where i left it. If the original page has numerous links to external sites i can see which one i last clicked on as it will still be showing active and i can move to the next.
If you can teach my mum how to open a new tab by right clicking then i’ll concede 
She can cope with tabs and knows that for things like holiday/hotel comparison sites that the results list will remain on one tab and each of the hotel sites will open in a new tab so she can review each one without having to click back each time. She can leave numerous tabs open and switch between to check details/compare between them and close the ones she doesn’t want. For me i can’t see how that is ‘broken’ it makes far more sense than leaving the results page having to click back then going to another result etc. i wouldn’t want to have to remember to right click and click again to open in a new tab.
each to his own i guess 
P.S. sorry if this has strayed away from the OP