10x engineers can be a good match for startups where shipping now is essential and for big businesses who need something done quickly (for a change, the bigger the company, the slower everything else).
The only cons of 10x engineers is that they will burn out and that they're incredibly rare. Advising 10x engineers to help out other and collaborate is also nice to give them a bit of down time so they don't burn out and leave for the next startup with a 50% raise.
That said, it's not like HR managers are able to distinguish between senior low productivity engineers and 10x engineers, so it doesn't matter. No company will have a strategy around employees productivity.
I disagree the 10x engineer is a myth, as an hiring manager, I can easily tell you who is a 10x engineer after working with them for a year or so.
You've 'lost' 80h effectively of productivity for the company (remember, mythical 10x), but you've gained 104h (32h+32h+81h/day5days) from your team, for a net 24h gain.
Of course, numbers are exaggerated, but the point remains the same: if you are a tech lead helping your team succeed is your primary job, not coding/design. You are the person who connects the lines of communication, removes obstacles, mentors the team on coding and design, and gets the team moving in one direction that aligns with the customer needs.
You probably will code, to fill in gaps and help out, but personally I find it's split around 5/2/2/1 - 5 parts are working with your team to guide them and help them overcome obstacles, 2 parts communicating with management and customers, 2 parts coding/design, and 1 part administrivia/training.