In Opera 12's tab settings, you have 3 choices for what happens when you close a tab. You had "activate the last active tab", "activate the next tab", and "Activate the first tab opened from the current tab". Also in Opera 12, you could choose to open a tab at the end of the tab bar or next to the current tab. There was also a setting for the order of how tabs were cycled.
Vivaldi has similar close options. It has a checkbox for "always activate related tab" and then a close order option with the choice of "Activate in recently used order", "Activate left in tab order", and "Activate right in tab order".
Point being, there are a bunch of ways to handle closing of tabs. Opera just needs the options so users can pick the way they want.