Exactly this conclusion I can make from SkyEng's article about how they decided to come up with a competency matrix for their leads.
They wrote a dozen competencies, including managerial, technical and... wow, evaluating their leads they understood that tech-leads aren't good enough in tech and they perform other "duties" as best they can. And they started teaching them. At the same time, at the end of the article there's a cliffhanger, they still haven't figured out what the problem is.
I honestly don't know what's right, it seems we just need to stop demanding that leads be the best at everything, and redistribute some of their responsibilities among different people. Again, the division into team leads, tech leads and all sorts of scrum masters with architects didn't just appear, if one person will do all this, they won't have time for anything, and if they do, they won't be able to develop. It seems that a lead is just something about responsibility for the whole team, this doesn't mean that this person should solve all problems around and inside this team solo. If they can do this, then they're a superstar, not a lead.
In general, the article is great for those who want to estimate what competencies leads have in different companies, but to imagine that someone alone will successfully combine all these roles in themselves - it's extremely difficult for me. A separate like deserves the recognition that before, people became leads who least of all didn't want to, and this isn't a very healthy situation at all. Absolute truth for almost all leads I've seen in my life.
If you look at the situation from the candidate's side from technical specialist to team lead, in general what reasonable justifications does this person have to go on such an adventure if they'll hang a bunch of new competencies on you in addition to old ones? You sit as a senior, close tasks, take side jobs. Bliss, right?