I do think this could be true. Your productivity is way more visible in a small company, execs actually know what you’re working on maybe from day-to-day and most definitely week-to-week. Slackers don’t last long and mediocre developers standout, now why they might be perceived as mediocre is another discussion. My first job was at a big corporation (~150,000 employees) and honestly I saw so much politics and fiefdoms and just generally low quality developers not doing much but they could sneak under the radar because they’re a small cog in the apparatus. My next company (~50-60 employees) the devs were definitely better and way more productive, but it also felt very performative/showy environment of what devs did every what and if you were perceived as not doing enough you definitely stood out. It was a very public, perhaps stressful, work environment with demos every 2 weeks.

I’ve mostly worked at small startups in my 30 year career, and been fortunate to work mostly with excellent founders and teams. Certainly that experience colors my convictions, as your experience colors yours.