Tongues are not meaningless words.
Romans 8:26-28
In the same way, the Spirit helps us in our weakness. We do not know what we ought to pray for, but the Spirit himself intercedes for us through wordless groans. 27 And he who searches our hearts knows the mind of the Spirit, because the Spirit intercedes for God’s people in accordance with the will of God. 28 And we know that in all things God works for the good of those who love him, who have been called according to his purpose.
I believe in spiritual gifts, but do a word study on what the KJV calls 'groanings which cannot be uttered' comparing the Greek word with 'as the Spirit gave them utterance.'
These groanings in Romans 8 cannot be uttered. Tongues clearly can be uttered because in Acts 2, they spoke in tongues as the Spirit gave them utterance. If they can't be uttered, you would'n't hear them.
I just don't get how using this as a passage for speaking in tongues ever got any mileage in the Pentecostal or Charismatic movement. It just doesn't hold water, IMO, and it doesn't make sense. Kenneth Hagin used a commentary from AW Pink where he described the groanings as words that could not be spoken with 'intelligible speech' or words to that effec.t And this is just arguing off the turn of phrase the commentator used, not the actually meaning of the words in the passage. Hagin was influential, and some of his ideas found some traction outside of the Word of Faith movement. Probably, like many other ideas, that could have not been original with him.
Whatever the case, I don't see any specific passages that say tongues are for intercession, though I would not say the Spirit could not use it that way.
We should accept speaking in tongues as a genuine gift, but that doesn't mean we have to accept everything every preacher or layperson says about speaking in tongues. Since speaking in tongues is a 'doctrinal distinctive' and has a lot to do with the identity of certain groups, there has been a tendency to really stretch the importance of the practice and sometimes the interpretation of passages. For example, when Paul says 'no man understandeth him', that's how tongues works in a meeting without interpretation. I don't see Paul's point as being about the importance of praying in tongues so the Devil can't hear you and interfere with your prayers being answered. Who cares if the Devil hears our prayers? Is the Prince of Persia going to get in the way? All authority on heaven and earth is given unto Jesus.
Then there is the idea that it is good for a whole church to get together and pray in tongues at the same time so they can all 'build their spirits' and be powerful for whatever comes next in the service. Why can't people 'build their spirit' at home. The prooftexts for these practices are in a passage about how speaking in tongues doesn't edify other people in the assembly unless it is interpreted.
There are extremes on both sides. One is people being too gung ho about speaking in tongues in a disorderly fashion, possibly a problem at Corinth, and the other is rejecting the practice even within Biblical guidelines.