For one, I can counter those with anecdotes from people I do know and trust. Like, I know directly from at least one very senior ex-Twitter engineer, who I worked directly with and whose technical chops I can vouch for (and who left before Elon took over, so you know, less chances of prejudice) that everything Elon said about Twitter engineering after he took over was absolute BS.
For another, I can point to boneheaded moves directly traceable to Elon, like eschewing LIDAR for Tesla FSD, that have endangered my own life on multiple occasions. Like, phantom braking is STILL a problem for in 2026, something that LIDAR would largely eliminate.
Just because he's built some very successful technical businesses does not mean he's technically strong. It is useful to know that cults of personality are cultivated. And especially for one like Elon (cf video game cheating scandal) when in doubt, it is probably a good idea to err towards "cultivated."