With reference to answers given here, it is mentioned multiple times that the main advantage is the ability to change/reinstall Ubuntu versions without losing configuration files. However, will a new install not require all you applications to be reinstalled ?
Living in countries where internet connections are slow, won't reinstalling the applications, updating OS, installing drivers just negate this advantage ? You might spend less time switching between Ubuntu versions' but you will spend as much time or more, making them usable each time.