This is excusable in a normal startup MVP, but not when you promote it all over Instagram.
I could see maybe trending topics as possibly a feature that would be nice to have at launch but the others?
The following are my thoughts if I were a PM choosing features.
search - What are you going to search for when the app is brand new? I believe we did have user search as I recall using it so you must be referring to content search.
DMs - Do we know what their anticipated user projections were going to be? I could see this feature being a worthless endeavor vs other things they could have done if the userbase ended up being small.
a web version - These guys are a mobile first company, the large % of users are on mobile, their existing web properties are either in maintenance mode(facebook) or just thin wrappers(instagram). I can see why this wasn't a priority.
non-Instagram account creation - Sounds like either this was a way to bypass overhead in their typical new user generation or they felt one click signup from IG would encourage more active users/reduce issues of bots which may not have been thought out at launch. It would be interesting to learn more about this unclear part of the infra.
Europe - Even for big company launches they typically american first, likely for the same reasons why we dont see big new tech companies ever launched from Europe anymore: too many little issues dealing with all the different countries in the union, issues with complying with various regulations.
Whatever they did Twitter folks or not, it was an extremely slick launch. Any Threads people reading this should pat themselves on the back.
On a side note: It was also fun watching Musk fuming that week when the Threads numbers came in. :D