The ruling party In Singapore has been in power since 1959, making it effectively a one party state. It may not be as authoritarian as some other countries, but the claim that it's a dictatorship is not as outrageous as you make it out to be.
My mental model for Singapore is that the People's Action Party (ruling party) is kind of like a BigCorp, and the other minor parties are like startups. Whenever one of the minor parties starts to do a little too well, the PAP does an "acquisition" of some of their platform. And thus society progresses without ever changing ruling parties.
A vote for the PAP is a vote to maintain the well-run technocratic status quo, and a vote for a minor party is a vote to tell the PAP about some policies you'd like them to adopt.
There is a legitimate debate to be had about district lines that might influence the fairness of the elections (gerrymandering), but many modern democracies have this issue.
Considering that the house of representatives is a fraction of one branch of the us government, your comment falls in the category of "not even wrong."
Japan's LDP was in power for 38 years straight and only was kicked out of office by an economic downturn and corruption scandal (which Singapore has tended to avoid better). It then returned to power again for the next 15 years.
That doesn't make Japan a dictatorship.