It’s mostly because LaTeX is deemed mature for its audience and features like these, while flashy, are not going to see much use day to day.
Most academics want to take plots they make in Matlab or whatever and put them into the template supplied by a journal and get an elegant looking document with well typeset equations and a bibTeX bibliography.
I hope this comment was made in jest or sarcasm. No respectable conference has replaced LaTeX with Word. Word is just a nightmare with typesetting scientific documents, with requirements for precise/fixed table & figure alignments, gutters, margin delineation etc. Although a word template is provided, almost no one uses it for the aforementioned reason.
Feel free to check this information's trustworthiness from any top-N engineering conference proceeding. Any year of your choice. It is easy to verify by looking at metadata for the PDF engine that made the document.
"We do not provide LaTeX templates as this generates technical issues with the IEEE process. If you nevertheless decide to use LaTeX,...", seems like a slight discouragement.
*This* is your pick for a top-N conference in engineering? Seriously, a random conference with motley of papers from all kinds of EE topics self-hosted in China. If you are making a joke argument for argument's sake, merry Christmas & please humor yourself elsewhere.
IEEE does not provide checking or process their sources because they pay only the token amount to keep IEEE banner. (IEEE recognition for local events and their commission/fees is a scam, but that's not what we are here for. These institutions pay a base charge of ~$3000 USD to get their paper indexed in IEEE Explore. It also gives name rights to use IEEE in conference name. For several other conferences, they also take 25% of the attendee's registration fee).
Source: Personally, in programme committee of two recognized international conferences: [International Conference on Image processing (ICIP) & International conference on Pattern recognition (ICPR). You can look up the validity of a conference on Google scholar metrics)]
Google Scholar Publications [1] This indexes venues by impact factor, citations etc. Basically a proxy for how established is the venue. You can further filter by application areas in Categories & Subcategories. For example [2] happens to be list for Computer Graphics only (among all other CS area)
Most academics want to take plots they make in Matlab or whatever and put them into the template supplied by a journal and get an elegant looking document with well typeset equations and a bibTeX bibliography.