Because Biblical tongues were languages that people understood. It means what the apostles spoke actually had structure and vocabulary that conveyed meaning. It is the meaning conveyed that proved the miraculous nature of it, and so Peter could say that the house of Cornelius had received the Spirit in the same way they did. In all cases it says they spoke in tongues and prophesied. There might be different ways to surmise what that means, but I think the best idea is that they all spoke in tongues, and their tongues were prophecies that were understood by the apostles. Therefore, the pattern follows the Biblical precedent, that all mentions of tongues in the NT are the same kind that was manifested in Acts 2. If you study it carefully, I think you'll see that this fits all cases, including 1 Cor. 14. And to claim that the gibberish spoken today is described in 1 Cor. 14 is to wrongly apply the text.
brief response here just to state what you say above is not factual
Paul first corrected the misuse of tongues in the Corinthian church (and tongues was far from the only item needing correction) BUT did he say stop it just stop it you are all just blabbering around? NO he did not. rather, he said this:
14 Follow the way of love and eagerly desire gifts of the Spirit, especially prophecy. 2
For anyone who speaks in a tongue does not speak to people but to God. Indeed, no one understands them; they utter mysteries by the Spirit. 3 But the one who prophesies speaks to people for their strengthening, encouraging and comfort. 4 Anyone who speaks in a tongue edifies themselves, but the one who prophesies edifies the church. 5 I would like every one of you to speak in tongues, but I would rather have you prophesy. The one who prophesies is greater than the one who speaks in tongues, unless someone interprets, so that the church may be edified.
Paul speaks of UNKNOWN languages that are identified as mysteries by the Spirit (of God). He say they are NOT speaking to people...as identified in the book of Acts
Paul says he would have everyone speak in tongues and states he does so more than anyone. do we read of Paul on his missionary journeys speaking in tongues to the people he preached to? no we do not because that was not the norm for preaching the gospel in the beginning of the church...yet it seems you and those with whom you agree, would have all tongues be as they were on the day of Pentecost and there is nothing in scripture to suggest that is so
so Paul is referring to the use of tongues in prayer...for the individual believer...in prayer, to edify and build up
don't ignore the above. this is actually the basic and most common use of tongues for the believer
and of course, we have tongues in church given for the edification of all gathered but if there is no interpreter, then no one should be speaking in tongues out loud
so there is an answer for you... no anger or dismissal and this type of response you will find in many threads but those who do not accept what is plainly taught in the Bible seem to just gloss it over and repeat ad infinitum. that all tongues should be interpreted and further. should be known languages only
the above short passage states otherwise and indicates a very different reality
do people abuse tongues? yes they do. not all that much has changed from when Paul corrected the Corinthians, but the other side of the coin, is often an appearance of godliness but without the power given by God to make it acceptable before Him. work that is done in the flesh is not acceptable to God, no matter how glorious it might appear to those who do not seem able to grasp that truth