Let me sum up the arguments.
What is a monopoly? Unless you need help, a political monopoly here would best describe PAP, because it has 75 more seats than the next highest opponent (WP), while WP has 7 more than any opposition party. Compare a 75-seat advantage to a 7-seat advantage - any kid can tell which is obviously a monopoly.
Someone said they dislike monopolies and therefore WP should lose Hougang. That's a strange theory. The result is that PAP ends up with 82 seats and WP ends up with 6. (Forget about the third candidate winning.) Now, why would anyone who dislike monopolies want PAP to further increase its monopoly by 2 seats to 77 (82-5) just to "reduce" WP's "monopoly" by 1 (from 6 to 5)? Is that person really against monopoly or pretending?
Next, let's examine the correlation between multi-corner fights and monopoly. For a long time, Singapore had straight fights but always end up with a monopoly. However in 1963, four corner fights were everywhere and opposition had about one-third of the seats (Barisan). This is also the norm in other countries like UK. No one has accused Labour or Tories of monopolising.
Because no second party was able to field 87 candidates by itself giving the impression that none are strong, we ended up with a monopoly. But if WP alone fields 87 candidates, some may see that as "monopolising", but if the result is PAP 55 to WP 32 because WP gave people the confidence, PAP is reduced from 81 to 55 - how is that monopolising? Rather, it should be DIS-monopolising.
So anyone who is against a monopoly but insist there should only be straight fights and no multi-corner fights, when straight fights are giving you higher chance of a monopoly, is being incoherent.
Don't get me wrong - I'm not saying which situation is my preferred situation, just questioning some of the weak theories that people try to put up.