I've seen some good very large digital surveys. We do some - geared towards measuring ad recall/lift - and I find them valuable, especially a giant sample on only two recall + head to head questions
You can always ask for gender/age and weight it but that's part of what I see as the problem. so many 'traditional' surveys i see make fairly large adjustments, lots of 'looking back' at past turnout and over fitting based on personal bias. Especially when weighting from very small sub-sample xtab e.g. hispanics. im not a pollster and that's just my still fairly-insider / polling adjacent insight
Another problem with digital surveys is most of the firms do opt-in panels, like having people register to take surveys and get paid on mechanical turk. and then they weight from there. I think this is a problem. The surveys we do run inside of mobile ads, similar to Google / FB Brand Lift surveys they go after those who saw the ads or a truly random sample, not a small biased group of survey panel
I wish pollsters would move towards very very large digital samples. You can't get a 15 minute survey but head-to-head you can get a huge sample for not a lot of money. And don't try to weight it to what you THINK the turnout will be. Break out likely voter or not. Do not add any inference or opinion or 'math'