Even with Germany it turned out that Angela Merkel did grave mistakes and Germans were able to find out about those only after she left office. Being continually in office gives you the ability to hide your trials. The longer you stay the easier it is for you to get elected.
That’s why it is very important to have a time limit in power.
The extreme case which you want to avoid is "politicians" (dictators) desperately clinging to power, because they did things that would get them killed if they ever lost their power, which is a vicious cycle.
I like the swiss model more where one party never gets full power, even if it means societal changes take more time to happen[1], it seems less risky to me as there is never one power grab whose decision can influence the next election by stuff like redistricting, puting clearly leaning judges to federal court, etc.
[1] famous example is the women right to vote in the general election happened in 1971 which is quite shameful
In many of the contemporary cultures (e.g., the post-Alexander greek kingdoms), being toppled from the heights of power would result in exile, imprisonment, or worse; in the republic, you could lose a battle as a general or step down from being consul and still lead a peaceful life afterwards.
One could argue that the change in this situation in the late republic directly resulted in it's downfall--Caesar crossed the Rubicon because he feared prosecution and imprisonment by his opponents once he lost his proconsular immunity.
A "required absence" is a thing in a number of sensitive positions, especially financial/regulated industries.
If it was not clear, I am not stating that anyone who is in office is automatically the most competent. However, the entire point of a democracy is that you have the option to fire bad candidates. And yet, with term limits, when you do get a competent candidate in office, you do not have the option to keep them in office.
Being the chief executive in a system like brazil's results in a lot of power, for several perfectly good reasons, but it does mean you have to build in safe guards against that power growing.
Regular elections are good, but not sufficient, as a study of recent world history would demonstrate.
Term limits are not a solution either, as a study of recent world history would demonstrate. Clearly there is a need to check power, but perhaps the mechanisms that check power should not also ensure you will never have a truly excellent leader && increase instability from flipflopping policies && give more opportunities for people who will abuse power to take office and ignore the term limits because that's what people who abuse power do. A term limit is only effective against a mildly bad candidate who is not truly willing to abuse their power, because if they are willing to abuse their power they can just ignore it. In that way, you've created a system that caps upside but leaves downside uncapped in practice.
Democracies shouldn't have a "leader", they should have functional governments and strong oppositions. Focusing on a single person never ends well.
The fall of that system then came about when politically ambitious characters started developing more personal and long-term relations with their troops.
I'd say that's an argument for term limits: you want them to get good but not set roots permanently.
What it loses in efficiency, it gains in avoiding centralization, cult of personality, and encouraging standardization.
"Rome's tradition of having to serve in 'lower offices' before the higher ones meant that when aristocrats inevitably ended up in charge of entire armies they had some level of practical experience and learnings to draw on while commanding".
But yes, much is made of Rome's redundancy in terms of military strength and there's a lot of states during that period that had A King who did everything and then died in a battle and then everything collapsed.
Obama could have had Bush against the wall at the Hague for his war crimes... and then Trump could have had Obama against the wall at the Hague for his war crimes... and then Biden could have had Trump... and on and one we go.