Recitation of the Quraan has an actual physical effect on the hearts and ruh of people (reciters and listeners). Take the example of Umar Ibn Khattab RA and the manner in which his heart changed in favour of Islam after his encounter with the few verses of the Quraan.
There are some verses, noted via the experience of pious people throughout the past till present, that are known to have a more 'powerful' effect than others.
For example, there's Ayat-ul Kursi. This is seen as a 'jalali'/powerful verse. It can be recited to protect against and ward off jinns/shayateen and it will do this job.
However, reciting too much (say 5000+ times a day) of a verse that is extremely powerful to begin with may lead to reciters experiencing some undesirable effects. In such quantities, it may be too much to handle. An overdose.
There are numerous anecdotes related to people going mad or insane after doing such lengthy unnecessary and strenous sessions of dhikr.
Hence, scholars of the sub continent have taken the precaution of informing the lay public on the powerful nature of some verses and advised against
excessive recitation of them.
That's the fact behind this jalali stuff. Nothing bidah there.
There has been no observable undesirable effect of
excessive sending of salawat on the Prophet Sallalahu Alaihe Wassalam and usually quite the opposite has happened throughout history (i.e. nothing but good has come out of it), hence it is seen as 'soft' and always promoted.
That's just my understanding. Allah knows best.