30 years ago there were no TAs because there were sufficient special schools for children with complex needs. The government then introduced a culture of "inclusion" with funding for TAs, now they have shredded that funding. So 99%of classrooms now have children in them with significantly disruptive behaviours (through lack of funding, not the children's fault), such as spitting/throwing furniture/hitting/kicking on a daily basis.
At the same time, teaching now is done very differently to 30 years ago, it's not as much "sit and listen to me talk then write" as much as 5 mins doing different carousels of activities, with partner talk and collaborative work etc. The modern approach requires significantly more planning and preparation to tailor it to the needs of your class than just showing up and chatting for an hour then drawing random picture.
Again, children now are different to 30 years ago. For whatever reasons, they now have significantly shorter attention spans, ability to conform to social norms such as active listening/taking turns/responding in regulated ways to peer on peer conflict. Given that schools are now having to teach these social skills, holidays impact on every aspect of a child's life. E.g. they forget how to use a knife and fork when away because their family let them eat with their hands in front of a TV.
Classrooms now are very, very different environments to even 20 years ago. The national curriculum, for example, changed in 2014. I don't think people who work outside of education can really get it, but the argument "it was fine when I was growing up so it will be fine now" doesn't really make sense, given all this.
It may have been fine for you. Great. That's not the reality I see day to day now, as a teacher. I'm all for bashing pointless government policy that fails children but I see the negative impact absenteeism and holidays have on pupils ALL THE TIME. That is my personal experience and why I don't take my own children out of school in termtime, despite also having family who live abroad.
Also respectfully, many parents who say it's fine have no clue about education at all e.g. they themselves can read and write well but, as they only have one 8 year old, they don't realise that that 8 year old can't read and write well enough. Why would they, when they don't see 30 8 year olds writing every day?
I find it odd that people don't value the opinions of teachers and schools about this to be honest. Like, if I want a medical opinion I'll ask a doctor and, because I'm not a doctor, I'll listen to it. Whereas parents ask for holiday in termtime, the schools say no and point parents to all the research that proves its bad for children's education, then some parents do it anyway. Just go on holiday in the holidays.