> What is the practical benefit in assigning the variants names based on the country of first detection?
It's really easy and natural to do that, since the name evolves straight out of the conversation. Especially when it's something new, unknown, and no one really understands what's going on.
> No valuable time is wasted plucking letters out of the Greek alphabet. The names are easy to remember. As long as they are applied consistently, who cares?
That's an artificial naming convention that had to be designed. And it might not be as practical as you assume it is. IIRC, NOAA recently abandoned a similar Greek-letter naming convention.
Some valuable time is also wasted with people needing to answer "WTF is that?" when all the sudden sources start talk about stuff like the "Beta variant," or people having to explicitly explain connections that would have been clear with a geographic name. As someone who has been following the news, the headline "India variant 2x more transmissible than UK variant," would have let me skip reading the article, since it told me everything new I needed to know (e.g. India outbreak caused by new more transmissible variant).