They get bogged.
I use my Yanmar B13 excavator for lifting.
Most recent job was loading 67 limestone blocks on my trailer. The hard part was that they had to be loaded under a carport which was slightly higher than the excavator cab roof, boom would have hit it at full height.
The blocks were 1 metre x 450 mm x 350 mm and really made the excavator grunt, especially with the boom fully extended to load the far side of the trailer. Original weight guesstimate was about 150 kg, revised version was 220+.
Alan