I was just spending long weekend at place with less perfect connectivity, that is 2-3 Mbs LTE... And the 11MB would have taken quite many seconds... Not exactly good user experience.
Good to know that Slack is not company to choose for user experience and efficiency.
I'm not sure, I've seen plenty of cases where programmers do stop and ask "Should we?" while management says "It's not ideal, but you have 4 hours allocated to shipping this things, so decide the "right" approach for achieving our OKRs" or similar.
Most of my professional experience is from working in smaller startups, grown into medium-sized ones, that I've picked to approach for work because I liked the programmers who already worked there, I'm guessing that's why :)
Consulting for various IT and IT-adjacent companies of all types of sizes, I certainly understand where you coming from, they tend to already be burned out (or something) enough to not ask questions anymore.
If you have mobility, it's worth shopping around for a decent place to work.
"I did what my manager asked me to. Asking questions is no in my job description. I've got kids to feed".
Did the product itself not give it away? ;)
This is an effect from no one prioritizing extra complexity that might / might not provide any tangible value.