The advantage of using tabs for indentation is that people can configure their editor to use the tab width they are comfortable with. The only argument against this seems to be that people don't want their code to look differently based on editor settings. However, since code is ultimately being written to be easy to read later, it seems much more beneficial to allow the reader to set the width to their preferred value.
On the other hand, because tabs have a different width in different environments, you will get aligning issues when you use it to format multi-line statements and other things.
An example of this is:
print(name + " is now " + age + "years old!")
But in this case the spacing in front of the second line has a very different purpose than that used to indent blocks. Since the purpose here is to align the second line with the
print( characters, the best solution here is to use spaces, since they're guaranteed to be as wide as each character in the line above.
To summarize, what is wrong with
...using tabs for indentation where everyone can set their own preferred width
...using spaces for aligning multi-line code where the width does matter
Since most of these questions are typically just tabs vs spaces, I hope to gain some more insight here about the advantages/disadvantages of using each for their own separate use cases.