On shirts (and swag):
My startup had a mascot at the end and I wish we would have had it upfront and had stickers.
It may seem trite but it's even documented in books like Managing the Unmanageable (or might have been Peopleware) that Apple made shirts for projects. When I worked at NatGeo we made internal swag for our project.
For me personally, living in a world of intangible software, stickers and shirts give me something physical I can hold in my hand. Something I can wear or point to and relate to what I'm doing.
On not knowing what you're doing:
I think the best people I've worked with are very intelligent and curious and do great work for things they don't understand because they ask a ton of questions to learn it which helps lead to epiphanies. It doesn't always shake out that way but with a group of motivated individuals it is so rewarding.
On everything being temporary:
Leaving design / trends aside and looking at our code-- our engineering-- this is absolutely true. For any devops engineers out here reading this: repeatability helps a TON. It's so much easier to migrate from bash scripts to RPM/Deb and from RPM/Deb to Docker. Or from [Puppet|Chef|Ansible|Salt] to [New Flavor Of The Week]. Once it's codified in some way it's so easy to move it forward. Automation == repeatability == freedom.
On people are everything:
Please, please, please don't hire smart jerks. Great, you're smart, you can program in 10 languages and worked at a FANG. If the team doesn't want to sit next to you and work with you on a project I am hoping to shape my life, my future and my family's outcomes 8+ hours a day (even remote) it's going to spoil the whole bunch.
I could go on and on for each section. I loved this article. Y'all will certainly find parts you disagree with but on the whole it is great and very applicable.