Why isn't the preposition "from" used to form self-sufficient phrasal verbs?

Some verbs usually take objects. Some take two. Others take different types of complement. Although most verbs can take more than one pattern, there are some which are nearly always transitive. They usually have to take an object.

The same is true of the prepositions which we find in so-called phrasal verbs. What the Original Poster has noticed is that from, like the prepositions to and at, is nearly always transitive. These prepositions must have a complement. For this reason they don't appear in 'intransitive phrasal verbs' either.

We can contrast these with other prepositions like back or away, which are intransitive and don't take noun phrase complements at all.

However, notice that because from, to and at, for example, don't take noun phrase complements, does not mean that they are always self-sufficient. Many intransitive verbs take other types of complement apart from noun phrases. For example, they may take preposition phrases: Look at me!. Or they might take verb phrases: I want to go! In exactly this way, many prepositions can take other types of phrase as a complement. This includes, for example, the preposition from: He came from out west or He jumped from behind the curtain.

^{This analysis is the one that you will find in the majority of modern reference grammars, such as Oxford Modern English Grammar, by Bas Aarts (2011). Traditional grammar regards intransitive prepositions as adverbs.}

---

Observations:

The Original Poster asks why, for example, from nearly always has a noun phrase complement. One theory is that from, at and to introduce points, not directions or areas. Instransitive prepositions usually in themselves represent areas, spaces or directions.

A second reason is that the other intransitive types of preposition that you can use without a noun phrase are deictic. So for example, if I say it went up, we know from the discourse that it went up from where it was, or from the ground. If we say He went away everyone knows we mean away from here or away from where we've just been talking about. If we say she walked out, we understand she walked out of the room, or out of the house or out of the meeting. However, the object of from normally indicates something that we can't readily identify by reference to here or now, or the ground or the sky. It most often doesn't have a readily identifiable anchor, or starting point. That place is rarely here, or where we've just been talking about (although it can be).

As mentioned in a comment, the following is possible:

"Heave to!"

It could be used as an imperative without anything else in the sentence.

---

Although nonstandard, I would argue that the following could also be used as an imperative:

"Come with!"

In context, it could be said to an individual by somebody in a group that is leaving to go somewhere.

(In short, Come with! would be the equivalent of Come with us! But it could also be a shortened version of You should come with!, which is slightly more common and doesn't include the us.)

However, it would not be normal, would sound a little strange, and would be understood to be a shortened version of a more familiar phrase.

Then again, it could be argued that something like Back off! is also a shortened version of something longer, that has only become familiar because of its use over time. As such, the two might not be considered essentially different—but how you define such a difference would be a matter of perspective.

This was the only example of something I could think of that used with, that might be considered a phrasal verb (it would depend on your interpretation), and that could stand on its own (be self-sufficient or intransitive, depending on your terminology).

---

The fact that this is not normal, however, is not a good answer to why we don't use from with phrasal verbs in this sense.

Saying that the particular word used with the verb is not normally intransitive, only moves the goalpost of the question—turning it into something like Well, why then do we not use from intransitively?

Unfortunately, although the question asked to not have a that's just the way it is answer, there may be no other response that can really be given.