Are there historical examples of Occam's Razor being useful to cryptography research? Previously, I asked what is the simplest digital signature scheme known, under the assumption simpler implementations could provide valuable insights on the nature of the problem.


  Among competing hypotheses, the one with the fewest assumptions should be selected. (...) In science, Occam's razor is used as a heuristic technique (discovery tool) to guide scientists in the development of theoretical models
  https://en.wikipedia.org/wiki/Occam's_razor


I specifically asked for implementations that didn't use number theory, because numeric operations (division, modulus) require some added complexity to implement in any "neutral" language that doesn't have numbers.

I received a plenty of negative comments claiming simpler schemes aren't proven to be secure, that simplicity is subjective and the general sentiment was that the question was pointless.

My question, thus, defies my own beliefs: has Occam's Razor ever proven useful for cryptography at all? Is there, for example, any historic occurrence of someone starting with a complex cryptographic scheme, looking from simpler solutions, and eventually finding answers that led to a better understanding of the problem itself?
The definition you cite says that "among competing hypotheses, the one with the fewest assumptions should be selected". If you take this literally and don't understand fewer assumptions as simpler, this principle is widely accepted in cryptographic research: Having a provably secure scheme means that it can be shown to satisfy some security definition under certain assumptions. If you propose a new scheme and prove its security under weaker (or less) assumptions than what was needed for previous schemes, this is considered to be a substantial contribution.

As an example, consider RSA. A necessary assumption for RSA to be secure is that factoring is hard. However, nobody has succeeded so far in proving that under that assumption, RSA is actually secure. There exist security proofs for (variants of) RSA, but they require additional assumptions. At Eurocrypt 2009, a paper [1] received the best paper award for proposing an encryption scheme that is provably secure assuming only that factoring is hard. That scheme is not simpler than RSA, but the hypothesis that it is secure can be based on fewer assumptions.

[1] Dennis Hofheinz, Eike Kiltz: Practical Chosen Ciphertext Secure Encryption from Factoring. EUROCRYPT 2009.