Is using ‘formulary apportionment’ as a method against multinational companies avoiding taxes through profit shifting as good an idea as it looks at first glance?

So, a while ago I had encountered the suggestion to mitigate tax avoidance by multinational companies by treating all of their branches as one entity.

The profits of every national branch would be summed then the resulting global income would be apportioned between all countries which have a branch based on some multi-factor formula, based on such factors as revenue, physical assets, and payroll, supposed to capture 'actual economic activity'; every country would then tax their own share of the multinational corporation's profits according to its own corporate tax regime. Thus, a company could no longer 'profit shift' enormous amounts of their taxable income by such mechanisms as 'transfer mispricing' and parking all their intellectual property in low-tax countries.

The idea I have encountered among others here:

(a short infographic) https://taxjustice.net/2019/11/21/unitary-tax-explained-infographic/

(discussed both this and also other proposals) https://taxjustice.net/2018/02/07/icrict-roadmap-taxing-multinationals/

It was also mentioned that not only could such 'formulary apportionment' be done by international agreements, but individual countries could also employ a 'formulary alternative minimum corporate tax' by themselves as a way to combat profit shifting away from their own country.

Whilst, it at a first glance appears to me, a layman, like it would likely be an effective measures; it is perfectly possible I might have missed a hidden flaw somewhere.

Not to mention that if such a proposal where to pass there likely would be lots of disagreement about the exact formula used; I presume different weightings would (dis)advantage different countries, so naturally countries would prefer weightings benefiting themselves more than others.

(Note, coincidentally when writing this post I noticed that concept also has its own Wikipedia page ( https://en.wikipedia.org/wiki/Formulary_apportionment ). There it was mentioned such methods also were used to apportion profits between US states, but not between the US and other countries.)

PS: Before somebody comes up with a suggestion in the vein of 'abolish corporate taxes and instead make the rich people who own corporations pay taxes'; yes that can be done, but explain that to the voters, not to mention that comes with its own problems like people incorporating themselves to avoid paying taxes.