If you care about ethics of journalism then yes you should obviously disclose a financial interest in what you write.
* Got paid a referral fee if I signed up
* Owned shares in the company
* Even was roommates with the founders/CEO but failed to mention it
I would trust that person less going forward.
If you want to be perceived as trustworthy, then you shouldn't say things that you have a hidden interest in saying.
Our investors (Spark, Amplify, Coil) are different to most, in that our partners are all highly technical.
Engineers, coders, CTOs who read the same research papers and attend the same technical conferences (CIDR, VLDB, SIGMOD, HYTRADBOI etc.).
In fact, that's how we met.