electricity is assur on shabbos because of boneh lfi the chazon ish in OC 50:9. Other isuurrim discussed in meorei eish from rav shlomo zalman are , tikun manah, maaveir etc.
texting will definitely be also the issur of kkosev. Reb shmuel vosner amongst other poskim mantain that typing on a computer is an issur deoraysah. Ain kan makom lehaarich bazeh
If you want you can add all sorts of other problems that are derabnan including muksteh ( kli shemelachto lissur!) uvdah dchol etc.
There is also no gerama at all in the issur of electricity.
And keep in mind that the people who text on shabbos are not doing it because they can write a teshuvah being mattir it. It is clearly an issur deoraysah which will make these peoples wine yayin nesech.
And being able to be mattir something with sevaros does not always help you. Many of the reformers and conservatives all had long teshuvas exploaining why what they did is muttar.