It seems like every HN Hiring post over the last 6 to 12 months is for "Founding Engineers". When you read the job ads, what they are actually looking for is a unicorn engineer who can build the entire product including Backend, FrontEnd and DevOps while also being an AI domain expert and any number of other demands.
This post is a perfect example of this: https://www.ycombinator.com/companies/roe-ai/jobs/CZrzxk6-founding-engineer
They usually offer 0.25% to 2.0% equity and 150k to 200k per year.
I guess I am curious if there is a reason they all started doing this at the same time? Was there some kind of YC memo telling them to do this?
Why would someone with those skills and qualifications go work for a startup building their entire product for 2% or less vs just building it for themselves and retaining 100% equity?
This whole trend seems super misguided and somewhat exploitative from the outside but it must be working if they are all doing it?
Personally I find the term "founding $employee" a bit oxymoronic and I tend to take it out of job ad titles on HN when I see it.
FWIW (<-- I am not a startup advisor!) my answer to your question is that any engineer who is inclined to "just build it for themselves and retain 100% equity" should do so. The only reason not to is if you don't want to, or have reason to believe that joining someone else's startup will be better for you in the long run.
Sometimes engineers want to work at an existing startup for a while, in order to learn things before starting their own. That seems legit to me. But you can also found your own startup without doing anything like that. Plenty of founders do, and YC is happy to fund them.