My issue isn't that people are flat out wrong that ele might not be as strong as some other specs for BLEEDING EDGE progression. My issue, personally, is that there are too many people on these forums and elsewhere who are making out that everyone is playing at a bleeding edge level and so the spec will be utter dogshite, when it actually won't for, let's face it, 99% of the playerbase.
The vast majority of people will be able to play Ele in Legion and be taken to raids as long as they are decent, reliable players. What is slightly irritating is that people like UCanDoSht spend their entire time shitting on the spec on internet forums. If it's so bad for your bleeding edge progression then fine, go and reroll Mage and pester them in their forums.
For most normal people, even people in the average mythic raiding guilds, Elemental will be absolutely fine to take with you.
I do find the amount of "grass is always greener" stuff on internet forums amusing. For example, some people on this thread have mentioned that Hunters do way more damage and so will be more useful in Mythic+. Take a stroll over to the hunter forums where 75% of them are screaming about how all their specs are boring as sin and masses of them are crying that their top DPS talent for MM (Barrage) is going to be unusable in Mythic+ because it pulls the entire instance along with everything in every other instance at the same time.
Specs always ebb and flow. If you want to always do the absolute top damage and always have at least one spec which will be top tier for bleeding edge progression then roll a Mage. Simple as. They've been the golden boys of WoW pretty much forever.
There are always better players though. You only need to look at Wrath Of the Lich King era Ensidia (the guild). Shadow Priests were by no means the best raiding DPS spec in the game yet their SPriests were almost always near the top of damage meters - because those players were just. that. good.
That was a bleeding edge progression guild - they took Spriests because those people were exceptional players. Could those players have done more DPS on a mage? Probably. Did they still get world first 25 man Mimiron Hardmode / Algalon 25? Yup.
TL;DR - unless you are genuinely competing for World firsts / world top 20 kills, you're probably not going to get benched just for being ele. If you are... Find a new guild.