I'll yield that it isn't a pure one party state. There is some room for difference of opinion whether you want to characterize it as one or not.

But let's not play the bullshit and borderline xenophobic, ad-hominem attack that it's just "outsiders" who "just don't understand." Or try and distinguish that it's people 'imposing their worldview' (something every human does no matter what they are arguing).

But don't take my word for it. Read what Lee Kuan Yew had to say himself[0]:

  The PAP represents the broad middle ground in society and attracts the best and brightest people into Government, LKY said last night.  He therefore did not see a two- or multi-party system emerging in Singapore soon.

This and other points, documented by Yeo Lay Hwee (Senior Fellow, Singapore Institute of International Affairs) , who even if she flip flops between suggesting Singapore is a one-party state, lists quite a few reasons why it is a reasoned viewpoint from an understood observer [1].

[0] https://eresources.nlb.gov.sg/newspapers/digitised/article/s...

[1] https://library.fes.de/pdf-files/iez/01361007.pdf