Text with multiple x="" values causes the characters to be broken up, within a word, so that parts of the word are in one place and parts are in another place. However, some scripts (like Arabic) require shaping across the entire word in order to be legible.

It's probably impossible to use things like kashidas to make text flow from one arbitrary place to another; however, we can at least require that the word be shaped correctly as if were placed contiguously.

This is conceptually similar to the hyphenation rules in CSS level 3. Those rules state:

When shaping scripts such as Arabic are allowed to break within words due to hyphenation, the characters must still be shaped as if the word were not broken (see §5.6 Shaping Across Intra-word Breaks).

and provides this descriptive example:

For example, if the Uyghur word “داميدى” were hyphenated, it would appear as not as .

The longer text in CSS is:

When shaping scripts such as Arabic wrap at unforced soft wrap opportunities within words ... the characters must still be shaped (their joining forms chosen) as if the word were still whole.