The advice to just get an LLC going first then convert to a C corp is fine for their stage, I won't argue against it. However, what you're saying in opposition to forming a C corp early doesn't feel very rigorous.

From my limited experience as a founder, forming a C corp early has made some things easier. The time we had to convert a California C corp to a Delaware C corp became messy and I imagine converting a {whatever state} LLC to a Delaware C corp also has the potential for being messy.

The conversion cost us a lot of money to have done right when instead taking boilerplate docs and simply forming in Delaware first would have been much easier.

Angels and incubators will generally want you to be a C corp first or convert ASAP, too (which is a valid option but I feel like there are other more important things to be spending cycles and money on). Raising money without worrying about converting your corporate structure is a pretty big reason to just do it as a C corp from the start.