what is the point of forcing people to vote so that the turnout is bigger

There is a very valid point to it. If people have not voted, you have no idea whether they have not voted because they do not like the candidates or because they cannot be bothered. If they spoil the vote it is most likely that they do not like the candidates. In addition, not everyone who is forced to vote will spoil their ballots. There will be some that vote for who they prefer and some who will vote tactically. In the Lincolshire mayor vote, for instance, we would have a much better idea of why 90% of the electorate did not vote for Jenkyns and, chances are, the vote may have gone differently.

As to "Authoritarianism at its worst", well, does anyone seriously think that being made to vote is worse than having your democratic reghts removed altogether? If so, then maybe some people should have their right to vote removed...