There's some conflicting logic in the fact that sometimes that kind of text communication is entirely high context, meaning someone is trying to communicate to you a level of interest, or disinterest, by their actions, and other times, it's entirely incidental, and moreso related to their specific personality traits, or other factors, rather than a gauge of their interest. Low context, meaning the unreturned text is just an unreturned text.
That's why hanging an entire relationship on texts, or using it as a bulwark is so emotionally fraught and essential for people. Like a high before the crash.
I text back and respond quickly, because it's the right thing to do, and it also makes the most sense communication wise, just strictly logically.
If you send someone a joke or an article, and they respond 4 days later or 4 hours, the timing and the context of the message is entirely changed in some cases.